Hmph. you jinxed me. Read your post and felt like a game. On mine, both cannons look for home on power up. BUT now I suddenly have an issue where the left cannon loads the first time, but the second time the plunger stays out, no ball loads and the cannon keeps cycling until you hit the left flipper. This points to a faulty opto, a harness issue and/or a loose connection. I have some investigating to do.........in addition to the middle of game reset, but I'm pretty sure that's a connector issue from the power driver to the MPU (or power driver needs bridge/caps replaced but that's unlikely) stay tuned.........

Yeah, I checked plunger freedom first thing and that's not the problem. I agree with borygard about software re:position at power up/down but I always let the machine reset completely for a new game i.e. wait for it to re-spot all the balls for a new game before I power it off. He also stated that if the cannons work during play with no errors, the cannons aren't the problem, but they sometimes do NOT work properly in game and with no errors. So his advice is sound--still sounds like a connection/opto problem in my cannon(s).