I need to take the solenoid off of a starter to find out why it only cranks some of the time. Looks like there are two screws. Isn't there a contact I can clean inside or something?

 

I've never overhauled an RX-7 starter/solenoid specifically (I just replace the assembly), but I have for other cars, and usually you can get an overhaul kit for about $20 with commutator brushes, oilite bushings, and some solenoid parts. YMMV. I just noticed that rockauto has brushes and solenoids. Look around.

 

Thanks. Ah, oilite bushings sound like those brass bushing that self-lubircate. Am I right?

 

Yes, "Oilite" is a trade name for a bushing made of sintered bronze so that it is somewhat porous and will absorb lubricant. They can last remarkably long if properly prepared and not abused. Very common in alternators and starters where there is little opportunity to do periodic lubeing.

The proper way to prepare an oilite bushing is to place it on the pad of one thumb with one opening down on the thumb and the other upwards, then fill the cup with motor oil, then press down at the top with your other thumb until oil seeps out of the pores in the side of the cup. Install with a press instead of banging (to retain oil).

Starter nose bushings always wear in the 90 degree quadrant away from the ring gear (it figures) so in a pinch you can simply rotate the bushing 90 or 180 degrees (after removing it) to bring some unworn bushing into play. Be sure to lube it, as above.

A worn bushing allows the commutator/brush relationship to change so that the starter won't work, and may even destroy the brushes. May also screw up some of the commutator segments too, but they're somewhat more durable so usually you just gotta cleanup or replace the brushes.