Quoted from nosro:

Whatever you may think of Wizard of Oz, you have to admit that Jersey Jack's commitment to code is unmatched. I think any reasonable person would have expected Woz code to have stopped development two years ago.

Quoted from Nokoro:

I believe I've discovered another bug, and it is potentially game ruining. I tested it with the glass off, and got it to repeat itself. I was hoping someone could try it on their machine and verify.
Here's the general situation: Sometimes when you have two balls locked and hit another ball up the ramp, the timing of the arm is a bit off and releases two balls. (This is adjustable, but even adjusting it, it can still happen from time to time.) When this happens, I don't want an unearned multiball, so I let one ball drain and play with the other ball. However, if I then hit the other ball up the ramp, it treats that as a drain, and I lose the ball. I do not believe this happened at all with the old code.
So, to test, please take the glass off and lock two balls. Then, without lighting "lock" push another ball up the ramp. The pin will release one ball, but you can release a second on purpose just by raising the arm with your hand. Let the first ball drain and keep the second ball. Wait a few seconds, hit some switches to prevent the game from going into search mode. Then, without lighting "lock" again, push the ball up the ramp. In my case, that always results in the machine thinking the ball has drained.
This sucks as it can ruin your game if the machine accidentally releases two balls. Again, the accidental release happens from time to time, and I don't believe the old code ever did this.
Can someone try to verify?