So, I'm putting the finishing touches on a BSD rebuild - managed to get most everything 100%, even the mist multiball (thanks to a replacement board!), however I'm still fighting one particular issue:

At startup, at random times, the system notes 'Pinball Missing'. It then 'looks' like it's going to start a 20 second countdown, but stops at 20 seconds, and never proceeds.

Other times, it says 'Pinball Missing', and it 'does' start the timer, and after 20 seconds allows the game to start.

And finally, at times it simply starts the game with no errors.

Per the manual, is states it may be a Ball Trough switch, or Ball Shooter switch, both of which test 100%, never an issue there.

The ONLY other issue I'm still chasing is the opto 72 for the Coffin Popper - for some reason it quit tonight. I haven't had a chance to meter the wires to check for proper voltages, and it has a new opto board (yep, replaced both opto boards). Could this be the reason for random 'pinball missing' errors? Can't imagine so.

Any sage advise (actually any advise is appreciated !!!)?

Well, I just found the issue with the opto 72 - the transmitter is 'gone'. There are solder joints on the board, but the IR LED is no longer there.

Looks like I'll be buying some IR LED's !

Still looking for opinions on the missing pinball issue, any thoughts?

The game only stages a ball for mist on what appears to be a random basis. I was under the impression that if a ball wasn't found there at start, the system would place one there, but that doesn't seem to be the case. And yes, there are four balls always in the game.

Well, after replacing the IR Led in 72, the game is now appearing to be playing nearly perfectly. It still on occasion will show 'magnet unload' errors at startup, but the long range opto checks out 100%, no issues. Close, but not quite 100%!

Meant to get back to this - the long range sensors were the issue - after replacing the IR diode in the sender, the game is now 100%. I didn't realize how much the game play depends on this working correctly, no wonder the manufacturer gives a way to turn the whole darn thing off.