One of my mates is selling some Middleburns with red bash and 22t (I think)# Mint condition really, hardly used. But they're SQ Taper, but a new BB is about £15 As said before, you could have cross threaded the arms, they would still screw on though. I guess the pedal axle thread would have cut a new thread into the arms? Due to being stronger metal? Like I said, only a guess. Maybe thy weren't tight enough at the start, came loose, but you still rode with it, and fecked the threads. Happened to my mate, so he got Tensiles Could get some of the new (not the cnc ones) Echo Cranks in 170mm with ISIS Taper? I've got the Sq taper 160mm on my Mod, feel nice, and quite a few people use them Helicoiling is another option, I think you just drill out the old thread, and helicoil it with the kit you get. The theads will be much stronger too, and should last a good while. But if you have the money for it, just get some new cranks, have a change. As said before, Tensiles or 'burns are your best bet. Look about for some selling 2nd hand if you have to