Your plan of attack should be to look at each of the issues independently, as they don't sound related yet.
Make sure you learn how to use the test menu.
Sound - try in test mode. Check your connectors, play with your volume potentemeter.
Ball eject - check the switch test to see if the trough is registering both balls. It won't activate otherwise. Use the coil test to make sure both the eject coil and the out hole coil are moving the balls to the right position.
Same process for your bagatelle eject. Probably a switch adjustment.
Magnasve can be tested with coil test too I think. But check your cab button and there is a relay under the playfield for it too.
If you cant make any progress, I'd call your tech back and see if he can figure it out.