a common problem for that is a small bevelled spring washer that sits at the back of the clutch pack. later bikes had a different angle for the spring which solved the problem. unsure of the change over year for the part needed. (although afro has just changed the one in his thou)
need to be replaced as a pair, although only one is bevelled, the other is just flat. and yes, new gasket. its funny, only suzuki fit them, and only suzuki have this problem…