In 4 years, rubber can stick to about anything very good! A modification to the suggestion above.... hit the retract button for just a second to just initially move each slide and then stop. This will move the slide out a tiny bit. It needs to be just enough you can get a finger between the rubber and the side of outside wall of the camper.
Now, that you can get your finger between the two, simply slide the finger all the way over the rubber, all sides. It' might be easier too, if you get some RV rubber slide-out conditioner to help soften it and let your finger slide a bit easier.
The idea is to make sure the rubber seal is not sticking to the side of the outside wall, so it won't rip to shreds the first time you try to retract. It may take a few minutes to do this, but it will take a lot longer to replace the rubber if it tears.