Hi,
I have a 1988 YJ 4.2L inline 6. I came out to start it this morning and just heard a click. The starter was trying to engage the flywheel but it was not bumping. I replaced the starter this evening but it is still not fully engaging. I understand that there may be another solenoid mounted on inside the engine compartment but what does it look like and could that be the problem? Please help. thanks
Kevin

this may sound stupid but did u check the obvious bad battery?
have also seen wires to it corrode and need replacing......

Since last post I have replaced the starter relay and checked the battery (12.5 v) Still not engaging. I'm wondering if it could be a bad ground or loose wire somewhere?

Two areas to look at. First I would have the battery load tested. Easy to do and quick at most any auto parts store. A battery can test good voltage yet not be able to deliver the amps required by the starter. The other thing I would check are all your cable terminals. Make sure that they are tight, have no corrosion, and that the copper wire is good at each terminal. You could have a connector that is still attached to the wire but many of the braids are broken and not able to allow good continuity.