starter disengaging

i have a 1988 ranger.. sometimes the starter will just disengage.. had starter checked it was fine.. the flywheel has some ware to it..
need shimmed??

By disengage do you mean completely? Its different if it drags than if it disengages. Keep in mind that if you checked it when off the vehicle it has no real load and will show like its working properly.

yes it disengages completely.. and sometimes when i try to start it will just spin and the motor wont turn over..

Sounds like either a starter problem or a flywheel problem without actually looking at it can't really help you. Has this happened before the starter that it has now?

Sounds like more of a starter problem. Looks like the solenoid disengages prematurely due to poor electrical contact or the starter gear is all chewed up.