Those are some nice shop-made adapters there. I spent some stupid money (again, not adding it up) on several original adapters out of laziness, but I expect that I'll make a bunch more adapters of my own.
I don't think any of the shaft couplings are broken on mine yet. Yet. The display offset knob is not only missing a chunk, but the higher numbers on the clear skirt are smudged to the point of being unreadable. Rather than trying to keep this machine looking factory new, I think I'll upgrade any plastic stuff that I need to replace. I'm not sure what I'll do about the display offset knob, but I have a plan for the broken plastic 10-turn pot mounting cup: I have some brass round bar that is big enough, and I'll turn a deluxe replacement on the lathe at work next week! That part doesn't function as an insulator; the pot shaft is grounded to the front panel anyway by the rectangular plate that goes on the inside of the panel. I'm calling it a cup instead of a bezel now, because I found it in the manual and that is what Tektronix called it. I guess they might have done that because the front panel was too thick to get the turns counter to fit the pot properly?
I'd rather have a functional safety cover in place than routinely bypassing the interlock, but I'll bypass it for some careful testing before I get around to making a replacement cover. I gather from the manual that the early production models had an interlock bypass button? I presume that Tek's lawyers had a fit over that and made them change it.