My old 7 string Rickenbacher needs tuners. I've not yet found a source for these open back types. I think they are Klusons. As you can see, I installed a knob in place of the crumbled plastic buttton. I'm afraid that others may fail as well. Also, the shaft of one of the singles is bend badly. I'd like to keep it as original as possible.
I have seen videos of people melting on new buttons, and I'm sure I could do this, but metal buttons are preferable.
Not Klusons. I think they're Waverlys, but I'm more certain of what they aren't than what they are.
Replacement buttons are out there; Stew-Mac sells them, among other suppliers. I find the easiest way is to clamp them in a vise and use a heat gun to heat up the shaft; get it hot enough and the button will slide right on and you're done. Other folks use a soldering iron as a heat source but I find they take forever.