G'day beetle.
I've had one for yonks and they do wear a bit in the gear area.
You problem sounds like it needs a service and most likely a bearing replacement since it is intermittant.
if it was constantly stiff, it would be lubrication problem (lack of or too much).
just a guess though.
I'd drop it in for a service and see how it gets on after that.
good luck!
Cheers, NS