Quoted from imagamejunky:
After WAY too many hours I'm about ready to wave the white flag. This TK lock is possibly the WORST lock mech in ALL of pinball! It works for a game or two and then it won't work for multiple games. It may correctly grab 4 balls in a row and then won't grab the next 20. The guide rod appears to slow or stop the travel of the ball most of the time.
I could really use some help here guys. I apologize because it's been beat to death. I've read multiple posts. I've followed the Stern PDF doc. I've checked the tolerances and rechecked them.
The only tolerance that is off is step 6 in the PDF. I've included a pic.
The doc says that the ramp rear wall should be slightly OUT 1/32 to 1/16" from the magnet cover. Mine is the opposite. My magnet cover is very slightly out from the ramp wall. Even with the magnet cover being OUT from the ramp wall, the distance from the guide rod to the magnet cover is within spec (25/32-13/16").
The instructions say to loosen the snug plate screw (red arrow on my pic) along with 4 screws on hex posts (mine only has 3) and the 2 at the ramp entrance. Then we're supposed to pull the ramp out away from the magnet cover and re-tighten everything. This does not work because as soon as I tighten the snug plate it pulls the ramp wall back. There isn't a way to keep the ramp wall forward AND tighten the snug plate.
Could this be causing all of my headaches with this mech? What have you guys done to be successful with this? Any help would be appreciated.
I've been where you are in terms of frustration with this mech. I've now gotten mine to work pretty well. There seem to be a lot of opinions on this, but here is what I did:
1. Put lock washers on the back where the solenoid plate is held to the back box. Even if you get it set up like it shows in the PDF it often doesn't stay there long. You need to have the ramp further forward (towards the player) than the magnet cover like the Stern document shows. Your ball is probably loosing some energy hitting the magnet cover. If you are tightening the snug plate screw that is probably the problem. In my opinion this screw isn't needed at all, and making it too tight will cause issues.
2. Make sure the mech moves freely. I've seen some put some tension in the form of a rubber band that pulls the joint at the back of the mech up which seems to help. Some have put WD-40 on here, but I don't think that is needed and will probably just collect dirt over time.
3. The rod needs to be as close to the back of the ramp as possible so the mech so the ball will be more on top of the rod than getting pinched by the rod if that makes sense. They don't provide any appropriate adjustment for this but many of us have put something between the ramp and the backboard (such as a washer covered in electrical tape). Obviously this needs to be done so the rod still moves freely. There is not a lot of play here but a little can go a long way.
4. The ball needs to enter the curve on the lateral part of the ramp to keep it from losing too much energy to the back wall of the ramp. You can lower the outside of the ramp slightly (it requires a different standoff to be used) but this is limited by hitting the mech if you go too low. You can also raise the medial side of the ramp with a washer. You can also loosen the screen on the right side at the bottom of the ramp by the flap. There is not a lot of potential for movement here but a little can go a long way. I've also heard of placing a thin triangular piece of rubber or other material under the reflective decal (it peels right off and is just as easily replaced) so that the wide part is at the top as to push the ball more lateral as it goes up the ramp.