Matt, there is a clear gel repair stuff "Goop" for shoes, for this, for that, that works well for repairs.
The key to unsticking the sliding windows is to LIFT the glass a bit by using the aforementioned putty handle knife or wood/plastic piece about 5/8" x 1" x 6" by putting the base up against the inside window frame and the side UNDER the window handle and carefully PRYING WITH EMPHASIS UPON LIFTING THE GLASS UPWARD. This more upward pressure lessens the chance of handle breakage and all you want is 1/16 - 1/8" upward movement to loosen things up.
We had a lot more problems with this in salt water and none of the sprays, silicone, whatever helped since they all seem to trap dust and debris. Keeping the channels clean is important.
Also, the outside drain flaps build up with spiders, bugs, dust, etc., but allow a good access point to force water backwards, up and out to keep things clean and to allow some space for any debris that accumulates to slide into. I spray a hard stream of water up these outside vents weekly and often seen lots of junk come flying out from the bottom of the window channel.
The best spray I found was "BOESHIELD", an expensive spray developed by Boeing for aircraft sliding components, BUT it also seemed to trap and hold dust and salt crystals. Lots of clear water flushing backwards thru vents and inside channels when open is the key. If stuck, LIFT UP on the front of the glass pane instead of pulling back. And,yes, somethimes you have to close the window more in order to release the latch.
John