In the shop manuel there's a description of checking and rebuilding the distributor, I think.
I think that the springs are supposed to be changed. They pull the weights back as the rpm's decrease, changing the timing as the engine slows.
You've got to make sure the weights don't bind anywhere or else they'll cause the advance/retard action the weights control to not work properly. There's also information about electrical insulation between the distributor housing and the 'lectric in the distributor.
Bushings should be changed, too.
This is why I bought a rebuilt distributor. I put it in the 216 in my '46, timed it, set the gap on the points and after figuring out that I had two plug wires crossed, the old mill starts on the first revolution and runs better than it ever has since I've gotten the truck three years ago!
The rebuilt distibutor came with new points and condenser and the grease cup was full!
I changed the distributor because I couldn't tune the engine well enough to provide easy starting. I knew the bushings were worn as the distibutor shaft had a lot of side to side play which changes the dwell. It had been so long since someone tightened the grease cup cap to lube the distributor shaft, the cap was frozen to the cup!
Jacques

Union, Justice and Confidence