Cool you did the right choice
Bought my first pinball 2 years ago and it is a Stargate too.
It plays well for month but problems comes so I'm in progress to restore it completely and hope it will survive me...
I'll be there for any question. I know every part of this game.
The first and more important things to do is to shunt all ground wires until it may burn transistor on A3 like it is preconised on pinrepair.com
Have fun