Starter occasionally spins but doesn’t engage
 

‘99 ‘Burb K2500 with the 7.4l / 454.

MOST of the time, the rig starts up just fine and everything is hunkie dory. But sometimes, the starter will spin, but not engage. If I switch it off then back on again, it’ll start up just fine.

I understand that’s generally due to the solenoid, and the bendix drive not getting pushed into the flywheel, right? The thing is, I actually replaced the starter 2 months ago. And the one I replaced was only a year old. So I’m on my third starter in as many years. All with the same spin-not-engaging issue, though the one I replaced 2 months ago worked fine for most of a year.

I don’t know what was on there originally, but the last two were remans. Replacement at this point is still covered under warranty, but I’m getting tired of replacing the starter. Anything else I should check? A different brand starter maybe?

sounds like a solenoid issue, but i hate to say it i dont really understand how this happens in a GM starter. the way it should work is the solenoid acts like an electric magnet and pulls a plunger back on one side of the plunger is a fork that will kick the bendix out to engage the flywheel or flexplate and on the other side of the plunger is a contact that acts like a relay connecting the heavy gauge battery wire to the starter due to the high amps the starer is getting ready to pull. some how even though the fork and the contacts are fully connected only one side will work, in your case the contact side. for some reason the fork doesnt kick the bendix out but will connect the contact

Maybe a missing tooth or worn-out tooth on the flexplate.

This. I had an old Buick Regal that would do the same thing. Every once in a while, the starter would just spin without turning the engine. I'd shift into neutral, roll the car a few feet, and then it'd start right up.