last night the belt came off and inspection this morning from the r.a.c said the pully had been spinning on itself and probably moved a few mm for the belt to come, he also said this is something that has happend over time as i could see where the rubbing has taken place on the pully, what is the likely damage of this causng probelms inside the crank itself as the pully and is it woodthrock key are knackered, what sort of price is a rebuild if its done damage inside

 

I had the same problem, I bought a new pulley and used locktight on the pulley, you will soon see if the key is damaged when you have the pulley off-Good luck