[PsychMan]

I think ive got to the crux of it. I've attached a picture focussing on the parts in question. There is a spring (circled) that attaches to the other circled piece (behind the cam wheel). The tension on this is not right, its too slack and based on what the manual says this is critical to size selection.

The straight part of the spring behind the cam has a bend in it, which suggests to me it is routed round the piece before leaving it. I cant seem to work out how to correctly route it. I think the bend must be there for a reason, but if I hook it round the bottom of the lever, the tension is too much.

If I could see how this spring is correctly routed I think that would quite possibly fix all this.

I see radiomuseum have the USA based sams manual for the RC121 MK2, and that does have exploded diagrams. Unfortunately I've hit my limit for today. Looking at my before pictures unfortunately doesnt show the routing of this spring.