Fresh off my adventure with a wobbly wheelbarrow, I embarked on a short, simple string trimmer job. HA, with some help from L, has done a whole world of weed whacking particularly while Satan’s Own Mower has been out of commission. We have two weed trimmers: a lightweight suburban-focused Black and Decker LSTE525 and a somewhat beefier DeWalt trimmer. For this short, quick job I chose the B&D.
For the first forty seconds or so it worked fine. Then it started slowing down. I swapped the battery for one I knew to be fully charged, but it still worked for a few seconds then slowed to a stop. When I checked it out, the head was kind of loose and wobbly (apparently this week’s theme). I could push on it, and it snapped back in place. Then it again worked fine for 20 seconds or so, and again it slowed to a stop.
I need to be fair to Black and Decker here. I bought this trimmer in March of 2021. It’s had fairly hard use and extremely hard use the last few months. It seems just as though something had come loose, so I started disassembling it to find out where to tighten things.
Unlike most string trimmers, there is no way to remove the trimming head on this one. It is fully integrated into the shaft of the reduction gear. Getting at it involves removing 14 T-15 screws and one #2 Philips screw, slicing a label, and prying the halves apart with a spudger. Of course, everything was covered with grass clippings but two of the screws were in deep shafts that were filled with what looked like black plastic that had been melted and re-congealed. It was a task getting the plastic bits out to where I could get the Torx driver to the screw.
Once I got it open, I could appreciate the clever design but I also discovered where the molten and re-congealed ABS plastic had come from. The reduction gear has a bearing that pushes against the top of the casing, and that holds the trimming head in place. The plastic came from that bearing seat. Probably the bearing seized at some point (it’s quite free now) and melted the plastic. Now there’s nothing to keep the head from wandering away from the enclosure until the reduction gear slips off the driving gear and binds.
If my 3-D printer was working, and if I was willing to invest a few hours of engineering time, I might be able to fabricate a new enclosure.
Again, unlike Satan’s Own Mower, this is a consumer-grade product designed for lightweight jobs that gave five years of heavy service and then died. Clearly, it wasn’t designed for repairability and the fact that you cannot replace the housing, while regrettable, is understandable. The mower’s failure was of a part that is designed to fail and be regularly replaced, but the manufacturer made it virtually impossible to repair.
Now I have a perfectly good motor and two viable batteries. I’m considering spending the $120 to replace it and just keeping the parts, as case failure is apparently uncommon (don’t see it mentioned in any reviews) but motor and battery failures are the main complaints. As I said, I have a heavy-duty DeWalt trimmer that does most of the heavy work around the compound, but I like having a little, lightweight trimmer for the lawn edges around the house.
After a couple of hours disassembling the B&D trimmer, I realized that a repair was hopeless and finished the “ten minute” trimming job using the DeWalt.
—2p
addendum 2026-10-10T15:50-10:00
I wonder… if I flattened out a small sheet of aluminum from a beverage can (I suppose I’d have to drink the beer first) if I could cut it into a shim that I can slide in where the ABS melted and provide a much sturdier end plate for the bearing. It’s worth a try. Stay tuned!