I think there is a small mini stepper in the backbox (AS relay) thats handles the match function and I think the alternating lights as well. The Gottlieb AS relays have a reputation of being very problematic. Make sure yours is working smoothly. I had to rebuild mine when I did my restoration.
Some pics of it in this thread:
https://pinside.com/pinball/forum/topic/centigrade-37-help-having-some-trouble-1.