I presume that the focusing scale goes to infinity.
Set the lens at infinity. Measure how far the focusing tab projects "back" from the lens mount flat plane. It should be 7.5mm. You can measure it with some sort of micrometer, or just put one of your 50mm lenses (at infinity) back to back with the 135, and see that the cam sticks out the same on both lenses.
If it doesn't stick out 7.5mm when focused at infinity, some fool started the helical at the wrong start.
Another check is that the roller on the RF push rod is about 1/4" from the end of the sloped cam inside the lens when at infinity.
Oh, if you're saying the focusing scale doesn't go to infinity, see where that sloped cam is when your lens is focused as distant as it can go. If this is the case, I bet that the roller on the push-rod is banging up against the large vertical discontinuity in the cam.
Sorry, I have no idea how to take this lens apart. Mine is so clean and smooth there's been no reason to. I can only guess that you start with the two large screws that hold the push-rod, and them remove the three small set-screws.
Hmm, I does look like there's a slotted ring in the rear, on the outside of the rear element, that probably is what holds the lens block in the focusing mount.
Looks like the helical "only" has 12 starts. Eleven wrong ways to put it together, one right.