My '98 New Holland TC29D wouldn't start, so we checked the battery (good) and then the starter (bad). We bench tested it and the pinion would turn but not go out. So we bought a new starter, bench tested it and it was good. Installed it on the tractor, and it would do the CLICK but wouldn't turn the flywheel. Removed it and checked the flywheel, which moved freely. Bench tested the new starter AGAIN, it was good, so we reinstalled it. Still no joy! All total we have R and R'd both starters a half dozen times. Anybody got any ideas?