Hello - Everyone!
I just wanted to share my experience with the IMI-101N High Torque Starter. First let me say that this is a high quality starter and hopefully my issue was an isolated problem. If not perhaps this might help you to fix yours also.
My starter was about a year old (out of warranty) and all of sudden stopped working...the solenoid would "click" but wouldn't spin over. Checked battery....good...checked wiring...good. Put my weak stock starter in and car fired off fine.
As I was carrying the IMI starter to my work bench I hear some strange rattling noises coming from inside the nose section (gear reduction part). I disassembled the starter and found very little wear in the solenoid and motor brushes...but when I opened the gear reduction housing....boom the problem. The reduction gear train consists of the pinion on the electric motor shaft and a spur gear on the starting/bendix shaft, and in the middle a counter gear that rides on 5 roller bearings. The counter gear on my starter is much thinner than space in housing, around 1/4" or more. This extra room allowed the gear to float too much on the shaft and allow the roller bearings to fall out of the plastic cage, thus locking the assembly up. I was lucky in that with the exception of some scars on the aluminum housing, nothing was broken and the roller bearings looked good. Fix was simply to use some washers under and on top of this counter gear to limit the lateral play on the shaft to prevent the roller bearings from falling out. There is still some free float in the gear but not to the extent anything can come loose.
I put the starter back together and it works like a charm and is much smoother and quieter than ever. This starter is based upon a Japanese starter with a custom nose section, so the problem or defect probably came from Nippon Denso rather than IMI. So if you have one of these starters and it stops working you might want to check out the gears for the same problem.