The mist ball is probably one of the coolest things in pinball. And to not have it work isn't a deal breaker, but it's something you definitely want to get working.

The mist ball is a magnet, motor, couple long range optos and a opto control board. Most likely it's the optos or the opto control board that are likely suspects.

Other things to look for are faded reds in the cabinet, broken ramps, planking of the playfield wood and cracked inserts. This game is supposed to have lightning flippers but if they were changed that's an easy thing to put back in.

If you disable mist, when you get the ball in the scoop to start mist multiball, it just kicks that ball out of the scoop and an additional ball from the shooter lane. Basically, you get to play the 2 ball multiball without having to knock the ball off the magnet.