Starter Motor or just the Solenoid?

Brushes and contacts are a real possibility. That is what I would guess.

IIRC, the solenoids on a lot of GM applications gave problems due to placement and quality. Placement means that they were too close to exhaust manifolds, etc, and they gave up when they got hot. In my run-ins with these, they often started working again when they cooled off.

If it had a heat shield around the starter and you removed it that too can cause problems with the starter. Otherwise is sounds like the starter is going. Does it not work when it's hot or anytime?? If you're tapping on the starter it's probably not a loose connection unless it's right at the starter.

The old GM starter brushes wear faster than other brands. My guess is that if you replace them, all will be well. If you really want to do it right, you can replace the solenoid, starter drive and bushings also. Look at the brushes first, though.

If the connections are good, put a starter on it. They are only 35 to

depending on how much you love the car, I might have it gone through by a good local auto electric shop rather than trading it in on a FLAPS reman. The former will be good for another 100K miles, the latter maybe only 50K or so :)

OR... my solution is to take 'em apart, clean everything, fix anything obviously broken, paint 'em real nice, and try again. THEN if I still have problems I know it's likely a winding and I *have* to take it to the shop. Of course I don't think Chevy solenoids are serviceable anymore...

nate

Does it do ANYTHING when it acts up?

Grab a remote start switch and connect it to bypass the solenoid the next time it happens. If you hit the switch and it turns over then the solenoid is going, if you still have to tap it then you probably have bad brushes and commutator wear.

OR just replace it with a good rebuild (or have that one rebuilt).