I have one of those on the way from Mobetta, I just got a bt100 from them and the piston jammed first ride. He's sending me a new top end that he cleaned up for me. I'm saving the zeda 80 for the roller bike. He's supposed to have some in stock this month
Using JB Weld on a saftey critical brake frame stud is not being wise with your money. it's too late now to repair properly because you have to completely clean up the stud and the metal it welds to and have someone who can braze re-attach it, at the right height and angle.