Swinks,

With the game off and unplugged, move the flippers by hand.  How do they feel?  Any binding or sticking?

First thing I would check is the EOS switch for both flippers.

Secondly I would check J109 & J110 on driver board (reseat)

If memory serves me correct the WH20 should be normally open, when flippers in their normal resting position.  Make sure they're not closed.

When were the flippers rebuilt last?  Might be time to put a kit through them.  Any pin which lands in my shop always gets a full kit regardless (not just plungers)..