I was just messing with my super vuk in a TFTC. I didn't need any force to get everything back together. You may have the wrong plunger or pin. The pin should be 3/32" x 7/16". If they're the right parts then this is how to assemble it. First install two rings on the vuk cup and push them all the way to the top. Put the big compression spring on the plunger and then push the plunger through the coil. Then put the little cup spring on the end of the plunger. The small diameter side of the spring faces the plunger and the larger end of the spring faces up to support the cup. Drop the last ring over the little cup spring for later. Then put the cup on and press it down on the spring a little bit until the hole in the plunger lines up with the slot in the cup. Now get the pin and slide it through. There should be little to no force needed. With the pin in there you should be able to let go of the cup and it should stay on the end of the plunger. With the spring tension pressing the cup upward, the pin should be held in. Be careful not to press the cup down or the tension is taken off and the pin will fall out. But you need to get that last ring on so that may happen. I put my finger over the side where the pin might fall out. Now get that last compression ring you placed over the cup spring and slide it up onto the cup. It will cover the opening where the pin slides in and prevent it from coming out. Push it up until it meets with the other two that you installed. That is basically all there is to it. Install the coil back onto the bracket and make sure your vuk switch wireform lever is sitting under the cup. If anyone needs more detail let me know and I will post pictures showing the assembly.

I'm bumping this topic because I just discovered the same issue from VUK kits I ordered from Mad Amusements. I've come to the conclusion that none of these online parts dealers realize the plunger's pinhole is simply too small for the metal pin they provide. Thankfully I didn't need the plunger part from the kit, but I can see it being very frustrating for those that do need the entire kit to work. Comparing my original parts to the rebuild kits, the pinhole is noticeably larger on the original plunger assembly. The only way I can see to correct the issue is to get a properly sized drill bit and drill out the pinhole to make it the correct size. You cannot force the pin in, so this must be done.

Just posting an update in that my idea of using a 3/32 drill bit worked perfectly to correct the hole size on the plungers (which were incorrectly sized at 5/64). It only took a few seconds to make the modification, and now the pins fit properly as they should.

Just a heads up for those thinking about buying VUK rebuild kits for their old DE/Sega/Stern what have you projects.

Glad you got it fixed.

For a few bucks, it's good to have a roll pin assortment kit around the shop:

http://www.harborfreight.com/315-piece-roll-pin-assortment-67682.html

Well the point is you shouldn't have to buy something like that. Clearly the parts manufacturer was in error here by setting the locking pin hole at 5/64 instead of 3/32.

Of course you shouldn't.

But how many times have you dropped a tiny roll pin and wasted 20 minutes trying to find it?

Or got a new game and found somebody just used a paperclip?

Or........

The rebuild kit comes with the pin.

Of course it does.

I just got some VUK rebuild kits for my R&B. I wish I would have read this thread first. I think they have another (new?) tolerance issue with the O.D. of the cap (ball cup/ball popper) "shaft" (the portion that goes over the plunger that you install the compression rings onto). It is noticeably bigger than the shaft on the ball cup I am replacing. I'm sure the old one had worn some, but the compression rings are almost impossible to get onto the new ball cup and once you do the ring tabs don't overlap at all and it I haven't been able to slide the ring up the shaft. I tried the compression rings that came with the rebuild kit on the old ball cup and they go on much easier (with just slightly less overlap than the old compression rings) and can be slid up and down the shaft. I'm not really sure what to do at this point.

BTW, I was able to force the roll pin into the plunger, although it is very tight. However, I think I will still enlarge that hole as directed in this thread.