Wanted Shimano EX300 rear derailleur

[onyerbike531]

Hi retrobikers
Does anyone happen to have a Shimano EX300 road rear derailleur they'd be willing to sell? The spring in the one on my bike has worn so it's not working as it should. Would it be possible to replace the spring even and if so does anyone know what spring it would accept?
I'd settle for any road Exage model EX300 400 or 500 or even a RSX but it would need to be the earlier 7 speed version.

Thanks

 

[tonyf39]

Have an RSX short cage, pulled fro a 90s machine from new.
The body is perfect, the back plates have a couple of marks from been in various boxes over the last 15+ years and the cable retaining nut went missing so has a basic replacement. I've cleaned the old grease off the B screw and put some copper grease so it's easy to adjust, the cable adjuster is bob on and of course the pulleys are unmarked.
Say £15 posted?