If your Craftsman V20 trimmer will not start, the battery will not charge, or the line will not feed, begin with the complete model number—not just “V20.” Craftsman sells V20 trimmers with different line sizes and feed systems, so steps and replacement parts that fit one model may not fit another. The detailed spool and charging steps below apply specifically to model CMCST900.
Identify your Craftsman V20 trimmer before troubleshooting
Find the complete model number on the tool, then look up that exact number on CRAFTSMAN’s product support page and open the matching product page’s “Documents and Manuals” section. If you cannot find a manual, contact CRAFTSMAN customer support. Use the manual for your exact model before changing line, opening the spool, or ordering parts.
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“V20” identifies a battery platform, not one universal trimmer setup. CRAFTSMAN’s listings show these differences:
| Model | Cutting swath | Feed system and line |
|---|---|---|
| CMCST900 | 13 inches (CRAFTSMAN specification, accessed 2026) | Automatic feed; 0.065-inch round nylon line (CRAFTSMAN specification, accessed 2026) |
| CMCST915B | 10 inches (CRAFTSMAN specification, accessed 2026) | Automatic feed; 0.065-inch line (CRAFTSMAN specification, accessed 2026); line shape not stated on the cited product listing |
| CMCST910M1 | 13 inches (CRAFTSMAN specification, accessed 2026) | Push-button feed; 0.080-inch twisted line (CRAFTSMAN specification, accessed 2026) |
Check your model’s manual for the specified line shape and diameter, feed method, and compatible spool. Do not assume that a line or replacement spool for one V20 model fits another.
#1 Best Overall
- Long Runtime: Finish the job with up to 63 minutes* of runtime on this weed trimmer
- 52% more power** - Taking on trimming jobs with a powerful motor that slices through thick grass
- Large Trim Area: Tackle wide areas in a single pass with a 13 in. cutting swath
- Adjustable Height Weed Eater: Stay comfortable while working with an adjustable handle that can be customized to your preference
- Versatile Operation: Grass trimmer and edger using a single tool with Turn-To-Edge functionality
Craftsman V20 trimmer won’t start or the battery won’t charge
For CMCST900, start with the battery and charger rather than assuming the trimmer needs a replacement part. CRAFTSMAN’s manual recommends checking that the battery is properly seated and charged, then interpreting the charger’s indicator lights using the manual.
- Remove and reseat the battery so it is properly connected to the tool or charger.
- Check the charger indicator behavior against the CMCST900 manual.
- If charging is paused, allow for temperature: the charger may suspend charging when the battery pack is too hot or too cold, then resume when the pack reaches a suitable temperature. Move the battery and charger to a moderate ambient temperature.
- Confirm the outlet works and that a wall switch has not turned it off.
- If charging still does not proceed, take the tool, battery, and charger to a service center as the manual directs.
Do not open or modify the battery pack. A no-start symptom alone does not establish that the battery has failed.
Rank #2
- Automatic Line Advance: The tool features an automatic .065-inch line feed system, eliminating the need for bumping and ensuring smooth operation as a reliable weed trimmer
- Efficient Cutting Swath: With a 13-inch cutting swath, the grass trimmer maximizes efficiency, helping you maintain a well-manicured lawn with less effort
- Ergonomic Telescoping Pole: The ergonomic telescoping pole makes it easy to switch from trimming to edging, so you can quickly transform the device into an effective edger lawn tool
- Extended Run Time: Two speed settings let you choose between more power or longer runtime, providing flexible performance for your electric weed wacker needs
- Quick Conversion: Easily converts from electric trimmer to lawn edger for versatile use around your yard
CMCST900 line will not feed or the spool is tangled
The CMCST900 manual describes automatic line advance during use. Do not bump this model on the ground to advance line. Line may wear more quickly against abrasive surfaces or in heavier weeds.
Clear a spool jam safely
- Remove the battery before opening or handling the spool area.
- Release the spool-cap tabs and remove the cap and spool.
- Clear broken line and debris from the spool area.
- Reinstall and route the line and spool exactly as shown in the CMCST900 manual. Make sure line is not trapped beneath the spool.
- If line extends beyond the trimming blade, cut it back to the blade.
Do not skip battery removal: the manual’s jam-clearing procedure begins by disconnecting the battery.
Rank #3
- EXTENDED RUN TIME: 2 Speed Setting lets you choose more power or more runtime
- TURN TO EDGE: For both edging and trimming
- ERGONOMIC TELESCOPING POLE: Ergonomic Telescoping Pole feature makes turning to edge a breeze
- AUTOMATIC LINE ADVANCE - Feeds 0.065-in. line automatically with no bumping required
- EFFICIENCY: 13-in. cutting swath allows for added efficiency
What size line does a Craftsman V20 trimmer take?
For CMCST900, use 0.065-inch (1.65 mm) round nylon monofilament line. CRAFTSMAN warns that serrated or heavier-gauge line can overload the motor and cause overheating. Confirm the exact model before buying line or a replacement spool.
That specification is not universal to V20 trimmers. For example, CRAFTSMAN lists the CMCST910M1 with 0.080-inch twisted line and push-button feed. Follow the manual for your model rather than substituting the CMCST900 line specification.
Rank #4
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When to stop troubleshooting and get service
Stop using the trimmer if its hub, spool, or another component is damaged. CRAFTSMAN’s CMCST900 manual advises inspection or repair of damaged components and directs owners to a service center for charging problems that persist after basic checks. Use the current CRAFTSMAN support information for service options; contact routes and hours can change.
Quick wins for a faster PC:
Clear out junk files and repair common Windows errorsFree Scan →Scan for outdated or missing drivers - takes under a minuteDriver Scan →The CMCST900 kit listing specifies a V20 2.0 Ah battery, charger, and 3-year limited warranty for that listed kit. Those inclusions and warranty terms may differ for another model or purchase configuration, so check the exact product listing and applicable warranty.
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