Hi Floyd
It's a fair few years since I had my 22, Tulena.
These fine little craft have now reached an age where it is difficult to see what might be original and what may have been altered or replaced, many times.
I would think your old jammers on the track are probably worn out and replacement is the best option.
On the main sheet the cams on the block are usually replaceable but yours look to be riveted, so drilling out and bolting could be an option if you can find clams to fit.
When it comes to rope sizes I worked on the basis of what felt right in the hand for the job, modern ropes are very strong and small diameters will be ample in strength, but cut in to your hands when pulling under load.
Philip