95% of the time BLANKING IS A SYMPTOM, not the cause.

blanking goes low when the monitored PIA port is not active. Sure the cap or timer chip could be the cause, but go to the monitored port before ripping out the the timer, if the port is not oscillating, then the blank is going to be low.

Any chance you dumped 120v into a switch or something? I had an accident once with a spool of solder sitting on the cabinet bottom of a WMS game. The game was off but the solder strand touched the hot side of the line filter, kapow, which much be before the power switch.