Out of curiosity I stripped the old shock as much as I could last night. Not a big job, but I'd read/heard before people telling horror tales of trying to remove the spring using car spring compressors.
So I removed the spring using car spring compressors.
Nitron had already checked the spring weight, but I wanted to see what condition the damping was in, having experienced bad fade.
First step then, on with the spring compressors

http://i97.photobucket.com/albums/l2...s/DSC00273.jpg

Give them a good winding up both sides and make sure they don't slip. I've pinged one off before, and it can make a mess of what it hits.
With the spring compressed enough to slide the retaining ring from underneath I did just that. This was the nerve wracking part; you've got to be sure the spring compressors aren't going to slip whilst you have your fingers in there, otherwise it's bye bye finger end.

http://i97.photobucket.com/albums/l2...s/DSC00274.jpg

Finally with the retainer removed, it's time to slack off the spring compressors and remove the spring, washer and preload ring. I was disappointed to notice the anodising had corroded on the shock body underneath the preload ring, and worse still the pin bolt at the clevis joint on the bottom was very rusty. The bike isn't even a year old.

http://i97.photobucket.com/albums/l2...s/DSC00275.jpg

So a clean up and check over and there's a weep on the piston rod seal, leaving a ring of oil on every compression. Other than that and the corrosion, it wasn't in too bad a shape. It's non rebuildable, though can be regassed.
So there you go, if you want to replace your spring, that's the way to do it. I didn't bother reassembling the shock, but in true Haynes fashion "reassembly is the reverse of disassembly".

I got my rear shock replaced under warranty but with less than 500 miles on it the replacement is going the same way so I'm worried about it falling over when it's on its side stand already! (it's got enough damage on its right hand side at the moment!).

I might look into getting a replacement sorted out in the new year.

Al.