The sliding door on my 83 has lately been sticking. I'm pretty
careful with it but I'm afraid a passenger will break the door handle
off, as those era door handles are prone to.

I think everything is in good mechanical condition, but I would
appreciate any suggestions that those who have encountered the
problem might offer.

I suspect that the rubber is sticking to the painted metal, though.
the reason that I suspect that is that if I close the door and try to
open it within a few minutes, it works perfectly. If I leave it for
hours or overnight, I have to carefully coax it open from the back
edge or push out from the inside.

Any kind of rubber lubricant recommended to try?

Thanks,

Jim