Sliding door will not open

I believe that gummi-pfledge is the correct product to use, rather than silicone spray.

One of the specific things that (as I understand it) the gummi pflege is supposed to do is ~not~ cause the seal to stick to whatever it seals against. I don't think air suspension bags suffer from the issue, do they?

If not, and you just want to protect the surface then gummi pflege would be an extravagant way to do it (because it's crazily expensive). I suspect in that case you might do better (or at least cheaper) with a light application of silicone spray grease, which dries to leave a thick enough coating to give protection?

On a T5, you can make a little extension to the lever that operates the catch, which takes up the slack. I did that on the Trooper around 5 years ago, and it's still working Ok. No doubt things are different on other models, but on the T5 you can't buy the cables separately, so you have to buy a complete mechanism - which IIRC is over £200!

But thankfully not needed in the OP's case...