On my old black/green commuter 550F1 I had a slipping clutch. Luckily I had some spare plates for the blue 550F2 that came with the bike, so I used them. Strangely though, the new ones were the same thickness as the old ones, which I still have. But the new ones worked a treat, &, together with some washers that I used to preload the springs, worked very well. There was no grabbiness or abruptness to the 550 operation...as has been said, maybe it was a 500F function.