Quoted from LMTLESS:
I replaced my subway walker assembly for the ball getting stuck in the subway situation... worked for a day and a half-- thinking it was a miracle that it was a hardware issue when it seemed so much like a software issue. Now, I'm back with the same issue where I have to disable the subway. How many of you are still seeing this problem with balls getting stuck (primarily after a portal lock or multiple players)? You peaked my interest that it still may be a software issue. Thoughts?
It could be an issue with aligning the forks in the center channel of the plastic so they don’t slightly bind or get blocked. I had the same issues on mine when I first got it, but after figuring out good alignment of the forks it’s been absolutely 100% reliable. I immediately went from frequent stuck fork & stuck ball issues to absolutely zero.
If the forks are not in the right alignment they can get stuck or bind enough to cause an issue. If alignment is only slightly off it’ll be an occasional problem. If alignment is off by more then the problems will be more frequent. It’s pretty easy to adjust the alignment since the screw mounts of the mech are open ended to allow for adjustment, so I really think it’s worth trying to see if changing alignment can fix it for you if you haven’t already tried it. Here’s the way I’ve found on mine that gets it set up to be reliable:
You’ll want to loosen the mounting screws of the metal mech housing and then from the right side of the machine look down the ball lock tunnel through the opening in the VUK. Align the forks so you can use your hand to pull the plunger on the mech so all forks come up through the channel in the plastic. When I did it the first time I found these two things resulted in good alignment and 100% reliability for me:
1) Make sure the two forks that come up with the plunger don’t even slightly bind even once when you pull rapidly many (5-10) times on the plunger. If there’s even a slight catch or snag then it means the alignment for those two forks isn’t quite right.
2) Make sure that when you look down the channel you see a little bit of space between the three forks that are usually up and the bottom edge (as you’re looking at it with the playfield up) of the center channel in the plastic. I found that if one of those three forks is up against an edge of the plastic then it will likely get stuck when you start playing.
I’ve taken it off and put it back on twice now and both times I found that when my alignment met those two conditions it worked 100%. The 2nd time I took it off was to file a taper at the end of the channel, and I got alignment correct on the first try that time by remembering those two keys from the first time I did it. I play the game a lot just about every night, so if it was a software issue I’d think I would have encountered at least one instance of trouble with it in the past month, but since aligning it about a month ago it’s been zero trouble for me.
It could be that there’s an issue with the lever connected to your plunger being loose or bent, or that your forks themselves are bent a bit and need to be straightened so they don’t get blocked. But either way I think it’s worth looking down the tunnel through the VUK and trying to align it the way I described to help figure out what’s causing your issue. Just an idea though. Hope it helps.