I'm wondering if the 'works with Demo time' isn't a massive red herring, have you switched the ROMs back to see if it still works with the Demo Time ROM? (Apologies if you have, I only skim read the thread)

Before buying anything, I would test 100% every single switch and opto related to the claw operation, if you look in the manual at the switch locations page this will help with that.

95% of the problems I've seen with the claw are to do with the claw opto, due to WMS cheaping out on the opto hardware. I can highly, highly recommend this board if the claw opto board is faulty:
http://www.greatlakesmodular.com/index.html?http://www.greatlakesmodular.com/products/pinball/dmcob.html

Not weird at all. Remember that Demo Time was (I believe) made using FreeWPC, which doesn't contain any factory code whatsoever, it is a ground up reimplementation. This means that it may have different requirements for the claw to work, for example the code for driving the switches may be more tolerant of a faulty opto, may work with optos that have failed etc etc.

Really curious to see what the problem is with this one. Might be worth updating your first post with everything you've tried so the information is all in one place.