I've had two PowerLite starter motors fail with the same fault. Not engaging with the ring gear (or whatever) about 80% of attempts. The motor runs with the key, though.
First one was bought about 10 years ago, and failed out of warranty. Thinking it an isolated fault, I bought another, as I was otherwise very pleased with its performance.
That now does the same. Just after the car was in a garage having the sump gasket changed.
Contacted PowerLite and arranged to send one back for repair. Sent the original, as then I can simply swap them over, and get the newer one repaired.
Got an email from them. Saying it's not economical to repair it. And offering a new one at a tiny discount.
And like many companies have tried to blame the failure on someone else. Here's what they said in the email:-
****************************1) The unit is 10 years old so has had quite a long service life
2) Our suspicion is that there has been a modification to the starter fitment aperture / bell housing, ring gear or flywheel, hence the issue of not engaging fully.****************************
1) It may be 10 years old, but for about half that time has been dry stored indoors. And the car unlikely to have done much more than 10,000 miles in the time it did work.2) The bullshit. Original engine never out of the car and original flywheel and ring gear. An auto, so not even a new clutch fitted. Also love to know how a gear drive can be worn so it sometimes works normally, sometimes not. It was obvious by the polished appearance where the gears meshed (over about half the width of the pinion), but there was little if any wear to the teeth to prevent it driving the ring gear.
After a bit of Googling, found an exploded view of the gear reduction Denso starter this is based on. And it looks like the overrun clutch/pinion assembly would be simple to change, if I can get a spare.