Before going any further - do you have schematics ?
Have a read of the "start up sequence" in Clay's guide - http://www.pinrepair.com/em/index3.htm#start
That's a starting base. Chasing things around will lead to more problems. 90% of faults on these games are within the player unit, but you need to read up on some theory.
I am waiting for the schematics to arrive, Daniel ddstoys is helping me out with that.
I have found quite a few things and yes you are correct they do lead to more problems, whilst fixing the jammed switches on the O relay I knocked the AX relay this gave me a false positive
I now have got to the point where the score motor and player unit are not endlessly cycling, and the score reels reset when the replay button is pushed but for some reason the hold relay is not coming in and the game over relay is latched on
I am thinking there is a problem with the coin unit at this stage so tomorrow I am going to service that