Jack2, PM or email you address and I will send you a replacement armature....
I am not familar with the MM measurements of comms, but what does 7.3 mm translate to?
Also, the MR springs may be a bit too heavy for a 10 turn....I doubt it had anything to do with the arm blowing up......its an electrical device and sometimes they just fail for no reason.
Raving Monkey.....the 4383 is a very good brush for the Ti.....most tend to use the 729 though, namely Chris Tosolini in both his Carpet Nats and Snowbirds wins.....the 777 brush works well in very hot enviroments on big tracks....
Espo......trav is probably at work.....staring at girls boobs.
Later EddieO