salinity

I am experiencing an intermittent no-start issue w/ my Jeep (1995 2.5L 5-speed 2WD). Issue started out of the blue a couple weeks ago after getting gas and has occurred a few more times since. When it occurs, I hear the fuel pump engage, door ajar buzzes, radio works, etc, but there is no crank or other signs of ignition-related life. There also seems to be no rhyme or reason as to when it starts and when it doesn't (e.g., not consistent w/ hot/cold engine, whacking the starter, etc). Also of potential note: I had some minor exhaust repair & an oil change done just prior to the issue manifesting itself.

As advised in other threads, I inspected and cleaned the battery terminals & wire connections (there was a little bit of corrosion), starter solenoid terminals/ wires (coated in a bit of oil), and a couple ground connections: (-) to body & (-) to engine block near dipstick. When the issue first occurred, I had trouble getting the 3rd party alarm to shut off (it typically lives in "valet mode", as I don't have a key fob for it, but inserting the key in the ignition should silence it). When it occurred yesterday, I noted I could move the wire on the (-) battery terminal a bit - after this it started and I tightened it down (although I'm not convinced this is the issue). Battery has 12.7v and she runs fine once started (1+hr drive to work this morning).

Are there any other connections or grounds I can check before pulling the starter? I'm trying to wait until it gets a bit warmer around here to get under and pull the starter if necessary (just cleaning connections was painful this weekend). Are there any other diagnostics I can go through to try and narrow down the issue? Thanks in advance.