Quoted from HowardR:If the Reset relay stays locked on
Quoted from byurick:It does make it past the initial stage of zeroing out the score reals
I'll rephrase @howardr's reply and ask, does the Reset relay ever release? Getting the score reels to zero and getting the Reset relay to recognize this are two different circuits. The Reset relay could be what's keeping your Score Motor running.
Also, I don't know that I'd assume that the game should reset with the playfield removed.
/Mark