note: if you have to glue up the plastic fiddly bits JB weld will not hold on some plastics. Generally I get good results with the stuff, but not this time.
Tried a bit on the AC knob and it hardens well, just doesn't stick. Got to be the type of plastic. The only two that JB doesn't stick to are Polypropylene and Polyethylene. So it's got to be Polypropylene. The other is plastic sheeting stuff.
Oh well, off to get some 3M epoxy for polypropylene.