FZ1 Gen 2 - rear shock

[FZ1obp]

Off to the tip at the weekend - just checking that the old shock of the Gen 2 can't be rebuilt? The spring on it is grey/silver while the 2nd hand replacement I put on the bike about 2 years ago is yellow and a bit harder.
Looking in manual I didn't see any spring rate/color charts - any ideas?


Many thanks