I have been having the exact same two problems on my Pro. I've only had it about a month or so now and it was working fine when I got it. I'm afraid that I've done something to mess it up while in the process of installing several mods, without knowing it.

I've done all the checks above and near as I can tell it looks in order. I'm not exactly sure what I should be looking for with regards to the stop and all. It definitely seems mechanical because when I turn off the pin while it is stuck, it does not drop.

What exactly goes bad with the coil stop? Is this something I could identify by inspecting it? Just not sure what I should be looking for. I can't really tell why mine is sticking. It doesn't happen all the time either. It's somewhat random.

I got under the hood again and took another look at my stuck flipper.

I noticed that the back of the coil stop(brass rivet/bushing on the outer side of the stop plate?) was loose by at least a few millimeters. It definitely had some visible play whereas the two main flipper stops were solid.

I tried removing the stop but there wasn't really anything I could do with it so put it back on. I also noticed a sort of washer around the stop that was slightly bent, I'm assuming as a sort of shock absorber, and normal. Flipper is still getting stuck though. It seems like it gets stuck magnetically. Manually the assembly seems fine and it springs back on its own when the coil isn't energized. I can get the flipper to drop back the majority of the time by pressing the flipper button halfway so as to only engage the main right flipper. I'm not sure of the correlation.

I took a look at the contacts for the flipper button assembly and the spacing seems fine to me, and it is visibly separating contact at the second stage when releasing the button.

I will try replacing the stop and while I'm at it, the plunger/link assembly and nylon tube too. Hopefully that will fix it as the game is pretty much unplayable right now.

Yeah, that was something that I picked up here before. It's good to reiterate it as it seems it is commonly unknown. I told my friend, who got me into pinball and owns a Tron, about this and watched his mind explode.

The reason I brought it up was because I thought there might have been some kind of bad contacting going on with the second leaf, and that it perhaps wasn't separating again when releasing the button(which it seems to do fine). But I'm still not getting the logic behind why, when the upper flipper gets stuck and pressing the button to only engage the first leaf, does it cause the upper flipper to drop. In my mind, it shouldn't be effecting the upper coil at all.

Nope.

The parts I ordered from PinballLife.com came in today. I replaced the two easiest things first, coil stop and sleave. BAM! That did the trick! It's rock solid now. So happy! Even the issue I had with mission selecting prematurely selecting missions went away(Which now I know was related).

I was also able to fix my "weak" auto plunger problem. I had followed Drainman's advice and used a pair of needle nose pliers to squeeze the two metal arms together a bit. It seemed to work for a short while but then got worse and the majority of the time it couldn't even successfully launch a ball all the way. So I tried the opposite and straightened them out completely. That did the trick. I'm thinking that wear and tear had cause them to slightly bend inward a bit. Now I know how to fix it if it ever gets weak again. And thanks Drainman for the tip cause it got me on the right track. If they had been spread apart then squeezing them together would have been the right choice.

Man, as a newb to pinball, being able to fix all this stuff on my own feels really good. Of course, I couldn't have done it without the help from you guys! Big thanks to all!