I have a 2000 year Trek 5200 OCLV bike. The previous owner was a pitcher o sweat and took very little care in stopping corrosion. I'm trying to clean up and replace parts that are needed. The front derailleur is not clamp on but mounts to the frame with 2 allen head bolts. My question is if I wish to replace this derailleur what am I looking for? This is not a clamp on and it doesn't look like a braze on either.