Check the ceramic capacitors at the switches under the playfield. Probably shorted. If so they can cause all kinds of havoc including not registering switches in gameplay but work in test mode. Remove them and see if the saucers wok in gameplay. Replace though, don't leave them out, because the system needs them to work properly. Its a 0.047 uf ceramic disk capacitor.
Check this out:
https://pinside.com/pinball/forum/topic/replacement-switch-capacitorolder-bally-pins