how do you get rid of the sticky yellow stuff?

hold down you belt and turn your fan by hand, start should turn, if not it may be locked up.

I had my charger slant 6 do nearly the same thing, with one exception, it was spinning fine one minute (i was not getting fire to the points so...) then it just did like yours and started clicking...

I removed cables from starter, cleaned and reinstalled, and that fixed the issue. All in all i wound up removing and cleaning:
both coil wires, starter positive wire, both battery terminals, and the negative side that bolts to the block. cleaned all of those and havent had an issue since.

it could still be your starter, but its worth a shot
hope this helped.

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69 charger with factory Slant 6 3-speed on the column