Front or back? I have a 68. I’d use some spray can silicon lube on front seals from the outside. I replaced my fr vent window rubber seals. Requires opening the doors + vent window removal. One hell of a job. I was restoring my doors and panels anyhow though.
In the back you’d need to pop the back seat out side metal panels off. Carefully peel back water shields (they might disintegrate if super old) and grease the tracks + crank gears.
Well, they are supposed to be stiff. There's a spring on the bottom pivot shaft putting pressure on the nylon washers to make it stiff. If you can get some silicone lube onto that, you should be fine. The small tube on a spray can, inserted into the rubber seal at the bottom center should do the job. It will creep down the shaft to the spring plate.