Rubber conditioner?

[Stinkaroonie]

My sliding window seals are all shrunken up and it's driving me crazy. I'm trying to find an aftermarket replacement with no luck. I'm thinking my only option is some rubber conditioner to help get the seal to go back to its original shape. Any product recommendations or tips would be appreciated

[Carbonized]

There is no Magic "rubber expender" that I know of. I had a severe case of shrinkage, the corners where coming out of the frame . I ordered a spare window from a junk yard, and got some 3M black weather-strip adhesive at my local Auto paint store. I had my windows out of the van, but I think the surgery can be done in situ. Slide one window all the way. Using a very sharp blade (Exacto knife) cut the rubber track on the straight part almost at the center of the bottom and one upright. Pull off the piece (1/4) of track and clean very well with soap and water, clean inside frame with alcohol or acetone . Using the adhesive as per 3M recommendation on the radiussed area only, bond track corner into frame, use a tongue depressor or paint mixing stick or spoon handle to push and press the track in place. Repeat 3 more times. You are now left with 4 or 6 gaps around the frame. Measure and cut filler pieces out of your spare track. Test fit before bonding then bond filler pieces into gaps. Bond cut ends of track onto frame, make sure there is no overlaps or curling rubber any where. Go back around and press one more time on all area with glue. You are Done!

It should look about like that (top and bottom 2or3x longer):

4350

[Stinkaroonie]

That's what I figured I'd have to do. Anyone have any extra seals for sale?

[Carbonized]

Have you had any chance ?
If not go to ROW52.com, search for an LE van and use a Puller service to pic and pull and ship to you. You only need a foot or two, and maybe a corner. Watch out when you cut your inserts, the track is asymmetric!