If you own a Black & Decker 40 V hedge trimmer (often found under model families like LHT24xx or similar) and it’s stopped cutting or is noisy, the culprit is frequently the motor or related motor components (brushes, armature, bearings). This post walks you through everything you need to know about getting a replacement motor for Black & Decker 40 V hedge trimmer 90576 — how to identify the right part, what replacement options exist (OEM vs aftermarket), a practical step-by-step replacement overview, cost expectations, safety tips, and where to buy genuine or compatible parts.
1) Confirm the model and the real problem (don’t assume it’s the motor)
Before buying a motor, confirm the trimmer’s model number and check simple diagnostics. Many Black & Decker hedge trimmers share parts across different model numbers — but not all motors are interchangeable. Look for the model plate or sticker on the trimmer housing (usually near the handle or battery compartment) and write it down. If your trimmer uses a removable battery, note the battery voltage (40 V in this case).
Quick checks that can save you money:
- Try a fully charged, known-good battery. If the trimmer runs fine, the issue may be the battery or battery connections.
- Smell for burning or listen for grinding: a burning electrical smell or metal grinding points more strongly to motor failure.
- Check brushes (if applicable) and visible wiring for wear or loose connectors — these are common, inexpensive fixes. Many vendors list motor brushes and armatures as separate, inexpensive parts. appliancerepair.homedepot.com
2) OEM parts vs aftermarket — pros and cons
You have two main choices:
OEM (original equipment manufacturer) motor/assembly
- Pros: Guaranteed fit (when you match model/type), often backed by manufacturer diagrams and support; tends to restore original performance.
- Cons: Can be more expensive; sometimes certain older parts are discontinued or backordered.
Aftermarket / generic replacement motors or motor housings
- Pros: Often cheaper, sometimes in stock when OEM is not.
- Cons: Fit and longevity can vary; may require slight modifications; warranties are seller-dependent.
Sellers such as appliance/parts retailers and specialist power-tool parts stores commonly list motor assemblies, brushes, armatures, and associated components for Black & Decker hedge trimmers. You’ll often find OEM part numbers and cross-reference diagrams on these sites. appliancerepair.homedepot.com+1
3) Common replacement parts you may need (not just the motor)
If the motor is failing you may also need:
- Motor assembly (complete unit) — easiest replacement if available. appliancerepair.homedepot.com
- Armature / rotor — sometimes the electrical windings or commutator fail and only the armature needs replacement. appliancerepair.homedepot.com
- Motor brushes & brush holders — cheap, wear out over time, replaceable without swapping the motor. Many parts vendors list brush kits by part number. appliancerepair.homedepot.com
- Bearings / shaft assemblies — noisy motor with play in the shaft often needs bearings.
- Motor housing / gear spindles — if mechanical damage occurred (example aftermarket combos available on retail sites). Amazon
4) Where to buy a replacement motor or parts
Reputable options include:
- Manufacturer / official parts pages — Black & Decker lists parts and accessories on their site; a good starting point for diagrams and OEM part numbers. If the model is still supported, the manufacturer can often point you to the exact motor assembly. BLACK+DECKER
- Major parts retailers (parts catalogs) — sites like Home Depot’s parts/appliance division and specialized parts warehouses list motor assemblies, armatures, brushes and more for Black & Decker hedge trimmers. These often include exploded diagrams and OEM part numbers. appliancerepair.homedepot.com+1
- Power tool replacement specialists — shops such as PowerToolReplacementParts and Fix.com stock both OEM and compatible parts and often have good search-by-model features. powertoolreplacementparts.com+1
- General marketplaces — Amazon and similar marketplaces sometimes carry complete replacement housings, motor+gear combos, or third-party replacements. Read reviews and confirm fitment before buying. Example listings show motor housing + gear combos for Black & Decker trimmers. Amazon
5) Cost expectations
- Brushes / brush holders: typically single-digit to low-tens USD.
- Armature or small motor components: mid-tens USD.
- Complete motor assembly: commonly ranges from ~$30 to $80+ depending on model and seller; OEM assemblies may cost more.
- Aftermarket motor housings/gear combos: prices vary but can be competitive with OEM options.
Availability and price depend on the exact model and whether parts are discontinued — older models sometimes have limited OEM stock, pushing buyers to aftermarket sources. Check parts catalogs with the exact model type for clearer pricing. appliancerepair.homedepot.com+1
6) Step-by-step — how a motor replacement typically goes (overview)
Warning: If you’re not comfortable with power tool repair, or the tool is under warranty, consider professional service. Always remove the battery before starting.
- Gather tools: screwdrivers (Torx/Phillips), socket set, pliers, multimeter, replacement parts, work gloves, safety glasses.
- Remove battery and ensure tool is fully powered down.
- Open housing: remove screws and separate both halves of the housing. Keep track of screw lengths and order.
- Document wiring: take photos of the wiring and connector positions — this prevents mistakes when reassembling.
- Inspect brushes & connectors: if brushes are worn, replace them first — sometimes that fixes the issue without replacing the motor. appliancerepair.homedepot.com
- Remove motor assembly: disconnect any plugs, unbolt motor mounting screws, and carefully extract the motor.
- Compare parts: match the old motor/armature to the replacement — confirm shaft length and connector type.
- Install new motor: reverse removal steps, reconnect wires, tighten mounts, but don’t over-torque plastic housings.
- Test before final assembly: install the battery, briefly test to confirm proper rotation and no odd noises. Then finish reassembly.
- Final test under load: test on small branches to confirm cutting performance.
If you encounter seized screws, stripped fasteners, or damaged wire insulation, pause and address those safely.
7) Troubleshooting when motor replacement doesn’t fix it
- Intermittent operation: suspect wiring harness, switch, or battery contact corrosion.
- Motor spins but blades bind: check gear/spindle, blade alignment, and lubrication; sometimes the gearbox (not motor) is the problem.
- Loud grinding: likely bearings or gear damage — replacing motor alone might not solve gearbox issues.
Parts suppliers often have diagrams and expert articles to help diagnose whether you need a motor, brushes, gearbox, or a full assembly. powertoolreplacementparts.com+1
8) Disposal, recycling, and environmental notes
Old motors contain magnets, copper windings, and other recyclable materials. Don’t throw them in regular trash — take the motor to an electronics recycling center, scrap metal recycler, or follow your local hazardous/waste disposal rules. Batteries especially must be recycled at approved drop-offs.
9) Final tips & checklist before purchase
- Double-check your trimmer model number and type (Type 1, Type 2, etc.). Parts listings are model-specific. partswarehouse.com
- Start by inspecting brushes and battery; they’re cheap fixes. appliancerepair.homedepot.com
- Prefer sellers who show exploded diagrams and part numbers — they make matching replacements far easier. appliancerepair.homedepot.com+1
- If the part is discontinued, consider a professional repair shop or a compatible aftermarket kit — but verify return policy and warranty. Amazon+1
Conclusion
A worn or failed motor doesn’t always mean the end of your Black & Decker 40 V hedge trimmer. With careful diagnosis, you can often replace the motor assembly, brushes, or armature at a fraction of the cost of replacing the whole tool. Start by confirming the model and running simple checks (battery, brushes), then consult trusted parts suppliers or the manufacturer for the exact OEM part number. If you prefer to DIY, follow safe repair procedures and test thoroughly before reassembly — and if in doubt, consider a professional to avoid further damage.
