Check the gap on the ramp bonus switch. If it's too close, vibration will set it off. If you're not sure stick a business card between the contacts and see if the problem goes away.

Ditto on the tilt switch adjustment.

If OK, then we'll look at more complicated things.

If you look at the contacts you'll see two metal arms that are pushed together when the switch is closed. See the pictures in the following article.

http://pinballrehab.com/1-articles/solid-state-repair/routine-maintenance/150-cleaning-gold-plated-contacts

When the switch is not closed it should have a gap of about .020" to .032". Very roughly a business card thickness (or buy some feeler gauges and be exact, but not really necessary).

Unfortunately this is not an exact science since most contacts have been bent to hell and back (meaning they may be more flexible than they should be, and will vibrate more than they should). As I said put a business card between the contacts and see if the problem goes away. Then go from there.

Start a game and just bang on the playfield.

This is how you know if many of the switches are adjusted correctly.

Check the rollover wire on the ramp switch to see if it got bent / wedged. Also check to see if the exposed section of the switch got hit by the ball. Activate the switch using the ball and adjust it so that it *just* registers when the ball passes through. That being said, probably best just to replace the switch if it's acting a little uppity like this.

As for the random tilts, is it the regular tilt (lose the ball 'Aaaak... Hey it's only pinball') or is it the slam tilt (XXXXXXX across the displays and game completely over)? When does it happen - when a certain switch is hit or a certain sequence completed? I had a problem on an Earthshaker with random tilts. When the spinner was...umm...spinning and I went up the fault ramp, it would tilt. Found that somebody had replaced the switch on the fault ramp but wired in the diode backwards. When both switches activated at the same time, it messed up the switch matrix and tripped the tilt switch.

On your game, the switch matrix shows the upper ramp switch is in the same column as the plumb bob tilt so there might be something to it. Check some of your other switches in the game and see if the diode is oriented the same way. Worth a shot.