It should be soft and pliable. Tears, rips and holes are red flags that the seals are bad. Corvette weather stripping is a known problem. Replacing all the seals is about a $600.00 expense, plus labor or time. Water damage in the interior could also mean bad weather stripping.

Both should move up and down, quietly and reasonably fast. If a window does not work, this most likely means a bad motor, but check the fuse panel to be sure. Check all switches. Early C4s used a wacky ribbon to drive them, they fail. Upgrading to later style window regulators is really the best choice.