I have had the top reciever cover off of my 1971 a couple of times for cleaning. This was worth doing but that old nylon has had an astounding number of shots fired through it.
The rifling still looks very good...it (the barrel) gets cleaned more than per say normal for a .22 but a lot of times was done because the rifle was brought in out of the cold to the warm and would sweat badly which makes this nessary.
Thanks for the link, I do have this paperwork somewhere and I will print yours if I cant find mine. I really do expect this rifle to outlive myself but mechanical breakdown's are always a possibility.