[Harp-L] ...Why do reeds go out?

[Chuck Linville <linvillec@xxxxxxxxxxxxxx>]

Hey y'all, happy weekend. I've been getting my feet wet with harp repair and re-tuning. Been playing for a few short years, I'm a machinist by experience, and I've always been interested in opening these things up, but never made the time. Well, now I have the time (unemployment can do that) and I am just fascinated with these things! Anyway, this tuning business has really got me wondering; what exactly makes them go out of tune? I've got a box of old harps from a friend and I am going through them, mostly Special 20s. I've been able to correct some by cleaning them. Others look indistinguishable from a good reed and I can't do anything a thing to cheer them up. All the gaps look fine and the rivet is solid. The only other thing I can imagine is metal fatigue from having been vibrated a gazillion times. Am I right? Thanks in advance! -chuck  (PS: If so, has anybody had success re-tempering?)