I had written a very long-winded story of what happened with my /5 and my process of diagnosing it, but unfortunately this site logged me out as I submitted. So I'll save you time and give you the short version:
Riding at highway speeds for an hour and a half. Stopped for a pitstop, started the bike up again and heard a very loud, disheartening grinding sound. It stopped when I pulled the clutch in, then resumed as I let it out. Towed it back home and thought it was either the clutch or gearbox. Took the gearbox out (a 5-speed installed by the P.O., not 4-speed) and found:
1. Water mixed with the gear oil
2. No felt on the pushrod, pushrod a bit rusty. Perhaps water and oil leaked into the clutch, causing a mess?
Bearings look a bit "burnt" on the sides, as do their insets in the casing cover. They roll fine though. Got the input shaft out fine, but cannot, for the life of me, get the other two out. Any suggestions on getting these out? Don't know if there is a circlip involved or not. The input shaft has an "X" scratched into it. Should the other two shafts have Xs also?
Does this grinding situation sound familiar to anyone?
Next will be checking the clutch out.