Thanks Gadge. I'll give that a go when I get back out to it. Hopefully that works. If its still playing up by the end of next week then I'm not sure what i'll do
It will require quite a bit of time and patience, over several sessions, to gradually work this free again. Just be prepared for that.
It's not a job that can be done 'all at once'- there's
no quick fix. That's the major reason why commercial workshops won't tackle this kind of task.
It is absolutely essential not to let it get any worse - if it seizes solid, that creates a whole new set of issues.