I'm trying to figure out why my idol is constantly triggering on its own on my RBION. I have read old threads about the topic, and it seems the most common cause is the window the optos shoot through gets dirty. I took the under playfield magnet and opto off, cleaned the window and opto, and it's still giving me the same problem. How common is it for the the idol/opto board to go bad? I can't think of much else that would be wrong, when I try to cut the opto connection manually (by hand) it seems like they register properly. Here's a video of the issue in action:

Thanks for the tips guys. I'll see what optos cost, and depending, I might try to replace those first. I've been playing with the wires disconnected and fortunately the game knows to compensate for it (the far left, lower tombstone will count as an idol hit and activate the magnet).

Since it's been mentioned, I do actually have an issue with the head opto. Although, I'm not sure if it's the opto or not--sometimes the ball will get stuck up there after hitting a lit head mode (the magnet doesn't activate and the ball sits up there). Not a huge deal, a quick slap on the side of the machine fixes it. Still, it wouldn't hurt to fix that too.

Not yet. I ended up blowing my flipper transistors about a month and a half ago and so my game has been out of commission since (hopefully should be back up soon once I order some new flipper coils). The tombstone was compensating for the Idol area when I disconnected the opto boards. Doing some of the recommendations posted earlier in the thread didn't help my situation. I am probably going to take the route of picking up a new opto board, they don't seem to be too expensive. Although, I am going to give that paper trick a shot to make sure the opto beams are lining up properly.

Sorry I never got back to this. I ended up replacing the opto board as well as the opto under the magnet (I didn't touch the one above the playfield, too hard to get to). It ended up fixing the issue.

The problem may have even just been the opto itself, but I replaced it and the board at the same time since it was cheap. The opto glowed much, much brighter after replacing it.

The opto will still test fine, but start screwing up during gameplay. I had a second RBION recently and it had the same problem. Opto replacement fixed it just like on my first machine. I'm not sure if it has anything to do with a dim opto beam (it was like that on both my machines before replacing), but when you put in a new one it will shine nice and bright under the idol.