Dura Ace 7700 rear mech problems

[Penthousepete]

Hi all
I've recently completed a retro bike build with Dura Ace 7700. All is good except for the fact I've been through 2 rear mechs. The problem I have had on each one is the thread for the cable/tension screw going into the casting is giving up and thus tension can't be obtained and indexing fails.
Has anyone experienced the same or have I just been super unlucky with eBay seconds? Annoying as I have bought the best looking one I could each time and they're not cheap!
Any help gratefully received!

[mattr]

They do corrode and jam/strip if not looked after.
Could you not save it by drilling out and helicoiling?

[ms6073]

Another thought is to take the knackered cable tension adjuster on the derailleur out of the equation by using an inline barrel adjuster up front.

[Asteroid]

I agree with this approach. Plus, I never knew the adjuster mounted directly on the derailleur ever went bad.
If you want to give it another whirl, I can sell you a very nice 7700 for $55 delivered within the U.S.
If memory serves, it's only got about 2k miles - always on good chains and cogs/rings.

Another thought is to take the knackered cable tension adjuster on the derailleur out of the equation by using an inline barrel adjuster up front.