Update:
Nick W: I tried squirting silicone lubricant in via a straw, from the cabin side through the belt-guide slot, but it evidently didn't reach the part sticking. I am reluctant to prise off the plastic cover to the inertia unit, because I fear that the only side accessible to me might contain the main spring.
I am therefore left with little alternative but to remove the whole unit..The single nut holding it to the metal bracket is reasonably accessible from the spare-wheel well, but unfortunately it is necessary to hold the top of the bolt at the same time, or they both rotate. . Apart from the very limited space, access is further restricted by the petrol filler-pipe. I fear removing that is very hazardous, especially as it is 25 years old.
I found a previous thread starting 2019 which refers to this problem:
http://www.talkmorgan.com/ubbthreads.php/topics/580283/Replacing_the_seat_belt_on_a_2The photos on there illustrate the access issues,, except he doesnt seem to have a petrol pipe in the way (probably because its a +4 and mine is a +8).
I am in the process of bending a 17mm spanner as advised to hold the head of the bolt, and borrowing a flexible ratchet spanner for the nut. I will keep you posted
