Sprint 1050 - Rear Shock Adjustment Seized

WD40 is ok but there are better penetrating oils. You will have some corrosion in there. White wine vinegar run down the threads and left for a few hours will dissolve rust.
A long engineer’s screwdriver and tangential whack with a hammer should then get the collar moving.

 

I recently had exactly that issue. I used a hex socket and lightly applied anti-clockwise/clockwise rocking until it freed. Only took a few rocks. A screwdriver, was getting nowhere. Now it works correctly. Hope that helps.

 

get some plusgas - better than WD... liberally spray and leave overnight... had seized plugs on my sprint RS - this did the trick although the pop sound when they finally released was bowel quiveringly worrying 8).... trick is to leave it to soak in and not rush out and try in 5 mins (speaking from experience here ) 8) worth a try anyway

 

Any joy with this?

I reckon if it's not moved in years, you'll be better stripping it off the bike otherwise you may end up breaking the mechanism

 

sounds like time to look on Ebay for a S/H one