OK, it's now fixed. I even removed the mast tang and re-riveted it in place after a good cleaning.

I have an idea - shoot it down if you think it won't work or if anyone has tried this.

Another hole in the mast base to correspond with the H-14 hole on the stepper may do the trick. If a pin is placed in both holes, the mast can't pop up. Maybe a double-pin tool that will go through both holes (so you don't have to bother with two pins). Even if the extra pin is smaller than the hole to give it a little play, it will keep the base from popping up.

I may try this and report back. Looking at the movement of the mechanism, it seems that two pins may do the trick.

Scott Laughlin
Omaha, Nebraska.