I'm looking at an aluminum mountain bike frame on ebay that has a crack in the headtube. The crack is on the top of the tube near the weld to the top tube and probably will not extend beyond the weld. It extends about 3/8 inch. This is a frame I am very interested in, but not if I'm simply buying something I'll have to throw in the recycle bin with old Coke cans. I'm concerned about the stress on the head and will that cause the crack to separate or is this nothing to be concerned about. Any experience with cracks in frames, especially aluminum or other comments are appreciated.