Great, thanks, I found that page in my manual.
I also had a look at the Bally Repair Manual (which can be found here):
http://www.scribd.com/doc/47481567/pin-repairOn page 82 it says the probable causes of a locked on LED are:
faulty U5
faulty U15
leaky C1
open R1
leaky CR1
faulty U17
Can I test any of those components with my DMM?
