In my experience it is highly unlikely to be the relay. There will be a globe near where the relay is mounted under the playfield. It needs to be present and working (see Marvin guides for detail - the extra load is required). Also, the lamp driver SCR for that globe obviously needs to be working. I had a Vector with a poor solder on the switched lamp bridge rectifier - while the lamps worked, there was not enough power for the solenoid expander board to operate properly.
I presume you have re-flowed the solder on all the pins on the expander board?
If you really want a new relay, Ed at GPE has them brand new.
cheers
Ian
