Strange cranking issue

Mornin' all. Bought a 96XJ with the 4.0 a few weeks back. Long story short it has a rear main seal, oil pan gasket leak and possibly at the oil filter, the starter is wet with oil from that area.

Problem is more and more often now when I turn the key, it begins cranking like it would, but the catch is just as its about to start (holding the key for a couple seconds) it almost sounds as if the starter motor is "skipping" or the batter dies for a split second and then continues giving the starter juice. 99% of the time i can just hold the key for a few seconds longer, and it still fires up, but once in the last 2 weeks it didn't start so i want to nail this before I end up needing a tow.

My thoughts are bad starter, or bad/intermittent connection? (I'm horrible with electrical)
Battery?
Something possibly wrong with trans or flywheel?? (its an automatic)
The actual ignition at the key is shorting almost making it seem like I'm letting the key go but then quickly engaging it again?

Any opinions much appreciated. Don't want to drop $$ on a starter if i dont have to, but would much rather it be that than a transmission/flywheel issue.

That oil can eventually find it's way inside the starter and cause contact issues for the brushes.

That clicking sound is usually low voltage, for whatever reason, battery connections, grounds, maybe even brushes.

It may be oil on the brushes, it may be severely worn brushes. I had one starter with one very bad brush. The starter sucked some serious Amps, slowed way down, caused the solenoid to chatter and made a sound like frying bacon.

Try cleaning the ground wire at the battery and block, I had same symptoms which turned out to be bad ground so worth a shot. Wire was right at block but needs cleaning.

Will try all of that...wasn't able to duplicate the problem until this morning. Never takes more than one try to start, but mid-crank it just sounds like its completely dead and then immediately begins cranking again. I'll look into these possibilities. Thanks!

I've had similar problems with mid crank. I remember the problem being from a failing starter.

Starters sometimes progressively become weaker and eventually wouldn't turn over on the second try. After repairing or replacing, engine consistently started up.

Pressure in the fuel line needs to consistently build up fast enough for the engine to start on the first try.

If the battery cranking power is low when first starting, the starter will pause, after a few seconds the alternator recovers the charging and the starter starts to turn over again.

Lack of battery cranking power can be caused from poor cables and connections.