Sorry if I am replying late in here doc.
Well, I would suggest not to replace the company fitted rubbers at all costs. If you are sure they are the problems, ask a nice denter to get them out clean with WD-40 first then use any Rubber conditioning product (Turtle, 7CF). And ask the denter to again fix that up nicely, if its loose, ask him to use double sided tape for better grip and fixture.
If you have replaced the channel rubbers by now. So make it a habbit then, they needs replacement every now and then. Replacement rubbers have no grip and become hard and brittle.
If going for replacement, no harm asking 3S dealers also for the complete door set. Let me know also how much they are charging for that. I will also ask my supplier for the cost comparison. Original rubbers are expensive though...
Hope that helps.