Keep the suckers warm! cold rubber is a ***** to deal with, I cut my hands up trying to install my side windows. The first one went in no prob, in the sunlight and fairly warm. The second went underway later that day, and the rubber has siezed up and was very cold. Impatient, I just pushed it in there, but had to use several large screwdrivers to pry the sucker in there (no good for weatherstripping rubber). Filling a bathtub with the hottest water you can get out of your tap and letting them warm in that is great, just make sure you dry them off completely.