It might be that the harness connector on the reversing switch (on top of the gearbox) is failing causing intermittent issues. The switch in my case was fine but the plastic switch housing had completely crumbled allowing the wiring to come loose. My symptoms were slightly different but itís easy enough to check.
Switches are either on or off, their fault condition is very much the same, either always on or always off. At most this should result in a fixed error - i.e. the reversing lights won't come on at all, ever. Bad connections tend to be random.
There is no systematic reason why a reversing switch should affect clutch related functions.
So where unrelated functions appear to fail together the most likely fault is something that they have in common, perhaps in the wiring where the return signal paths meet. So OldSmokeys experience seems to reflect the most likely cause, while wacjacs problem may have been cured by disturbing and reconnecting wiring rather than by the replacement of the switch.
Diagnostics would be improved if people would ask to be given the 'faulty' item, so in wacjacs case if the replaced switch was shown to be good, it would have been eliminated from the diagnosis rather than being blamed as the cause. (I'm not saying it wasn't, just theorising).
I'm having my gearbox done next week - I'm asking to have all the replaced bearings given back to me so that I can better determine what the fault was and so if another member of the forum has a similar problem I can at least offer a checked possible diagnosis.
So Marknewton, you have two suggested causes, a switch or wiring. I'd like to know what was found when you get it fixed - and if a switch was blamed, you might get it back and see if it really was faulty!