I am the owner of a Trek Y22 mountain bike. I have found a small crack that runs along one of the welds in the rear swing arm assembly near the pivot point. I like the bike, but have been told that the swing arm is no longer available. Could it be a reasonable repair for someone familiar with welding aluminum? I was going to try to find someone at one of our local small aircraft repair shops who might like to take it on. I fear that the heat generated when TIG welding the bad seam will knock everything out of alignment. If that happens, I have no way of getting things back to normal, so I don't know if it's even worth bothering with. Any ideas?