If only one solenoid is not working, here is your 2 levels of repair that may be needed:

1 - Driver and pre-driver transistor - straightforward
2 - driver, pre-driver transistor and maybe a 7408 IC - a bit fiddly but reasonably straightforward

You do step 1 first anyway, so step 2 is "just" swapping an IC...

I'd be carefully checking the rest of the machine, to make sure no other drivers have been taken out (flashers, lamps, other solenoids). Probably not, but check anyway

Cheers
JAcob