Literally thinking outside of the box here but when the spigot bearing fails, it can also dry out and go rusty, it can make some very odd noises. Can also make gear selection difficult too as the clutch disc moves about. Try reversing slowly up a steep driveway off the flat. As the rear wheels move onto the slope and the rear end rises as you slip the clutch, listen for strange noises. Been there, heard that, found rusty bearing which was breaking up. New bearing and spendy new clutch at the same time, drive plate material had some cracks in it, brought back a nice smooth and light(!) clutch and a better change.