I have my box in bits at present, the peg that engages the grove was worn on mine, I turned it through 90 degrees to get the un-worn part on the grove.
The worm shaft have very small ball and cup bearing, they are adjusted by shims under the end cover, might be worth taking a shim out and tighten the cover back a bit at a time and get a feel for the play as you go, also it looks to me the only way to drain the old oil.
Years ago I had to fit a new U/J shaft, when that gave out. it looks the weakest point in the system to me. In fact it is intended to be a weak point in the event of a crash.
Jon the Chief
