The associated driver and maybe pre driver
Have failed, look in the manual at the schematics , there will be a page with the switch matrix, there you can narrow it down to likely the tip transistor (driver) that fires those coils

Could be a fried connector, cracked solder joint where the connector plugs on the board, or a fault on the board itself, remove an post a few pics of the board

I always liked rollergames!

Glad it was simple, having the schematic and understanding it helps , at least until your familiar with the boardset an how they relate

Cool thing is when you get other system 11 games you'll be more comfortable when troubleshooting