Well that was pretty painless.
Tension off the belt...
Old pulley off...yep, that's stuffed...
New one installed and tightened up...
Paint marker is to allow me to keep an eye on it to be sure the bolt doesn't try to unscrew itself for a few days before I put the wheel arch liner back in.
Yes, I did thread lock it too...
The replacement pulley I bought was a Febi Bilstein one (part no 31102), the going rate for which is about £65 at the time of writing. There were some no-name ones for less than half that, but with how important a component this is (especially in a green blooded Citroen!) it seemed worth spending a few quid to get a brand I trust. The Gates one at North of £100 just seemed a bit excessive though.
This does appear to have restored normality I'm glad to report. The belt seems a little noisier than I remember, but in the same breath it's a brand new one so will need to bed in a bit, also the battery is pretty low (car's been sitting since mid July...), so the alternator will be pulling a lot of power from the belt. Will keep an eye on it.
Tomorrow's task is to attack the LHM tank with a box of decent hose clips. I know I've got an issue with it aerating the fluid, and one of the returns is obviously weeping given that this message is what I'm left with within a few hundred miles of cleaning the reservoir.
Hopefully a box of hose clips will resolve both of these problems.
Observations not having driven it for a month:
The clutch is so light that it doesn't feel like the pedal is connected to anything.
Man it's comfy.
Holy hell it's quick...the prerequisite grin emerged the first time full boost arrived.
Have I mentioned it's comfy?
Yep...have missed driving it.
Once again slapping myself on the wrist for ever considering selling it. Even if it does cost me utterly stupid amounts of money to insure.