I'd guess the rear end is original, I have a 93 team with an alloy rear end. I would hazard a guess that the rear end pictured has been resprayed, blue decals to match. It's also got the canti rocker which is often removed and lost.
Shock rebuild wise it's a challenge in the UK. It's nitrogen charged and old, though i don't think it's a complicated shock with proprietary parts.
A while ago now I did find that this place did rebuilds, if they still do I couldn't say
https://mickgardnerracing.com/mountain-bikes
There may be other places in the UK
Noleen still exist and will service but shipping and taxes kill that idea off really.
Here's a link to a mod that adds an air valve to replace the nitrogen.
Inspired by RC300's thread...
http://www.retrobike.co.uk/forum/viewtopic.php?t=54021&highlight=
ive modded my own NR-1 with an air valve
Dismantled shock...
Fully rebuilt shock with 600lb rockshox spring..
how to do it...
first a disclaimer... if you F*ck your shock up doing this... its not my fault!
1: remove the shock from the bike...
2: remove the spring from the shock..
3: remove the philips screw from the end of the...
If you find anywhere that does service the noleen, do share. I'd be interested to know.