I have a bicycle frame made from AZ61 magnesium. One of the rear drop- outs (the part where the rear wheel attaches) broke. It appears that this part is made from cast magnesium (the rest of the bike is TIG welded tubing). Right where it broke, there is a hole for a bolt which is used to align the wheel. This bolt is not strictly necessary, and it undoubtely weakens the area.
Here are some photos:
Any suggestions on how to find a welder capable (and willing) to fix this?