If it's the same as the 1100 Evo, then it'll be a Sachs, which I don't think is rebuildable.
This could be just the excuse you need to fit an upgraded shock. I've got an Öhlins DU737 on mine, which should also fit yours, but there are loads of other options available.
Nitron get good reviews for quality and value and Boris fitted a very nice example to his Evo recently.
http://www.ukmonster.co.uk/monster/s...ad.php?t=55432
You'd also be able to have it tailored to your exact weight and riding style.
Alternatively, maybe Boris would be prepared to sell you his old Sachs unit...