the shaft that operates the clutch (from the actuating lever) has a ball bearing at the clutch end. It's about 4mm dia. Have a look at pg 152 of the manual.
That's the only ball bearing I know of, that's not in a race. If you had lost a ball out of a race, there'd be trouble.
If it has been in there since production, it couldn't do any damage. It would just sit on the bottom of the sump.
Check the clutch actuating rod. See if it's got a ball at the end of it!