In article ,
Murmansk writes
OP here

Well, the bolt would only turn a quarter turn, I flooded it with oil
and worked it for half an hour but no joy so with the help of my
neighbour and a metre long bit of scaffolding pole attached to the
spanner I eventually got the bolt out.

Every turn of the bolt took a huge amount of effort even with the
scaffolding pole, the thread is knackered. Only question remaining is
what the thread in the nut that's welded to the mechanism is like -
probably knackered too!

I'll have to see if Witter will sell me a new mechanism
Have you cross threaded it putting it in?
--
bert