Decided to stay with a "natural" lubricant for the zippers so I dug out a can of my homemade muzzleloader lube (a mix of neatsfoot oil and beeswax).
Hmmmmm ...........how to easily apply it? (it's a paste similar to "bore butter" for muzzleloaders)
Tried a cotton cleaning patch, but it was too difficult to hold on to while attempting to spread the lube. Then it hit me
an old jersey glove 
Dip an index finger in the lube, rub it on the thumb, then rub it on each side of the opened zipper. Worked like a charm and the zippers glide smoothly now!
I also took time to paint the outside of the windows flat black like the other blind.
This gives the blind a similar appearance with the windows open or closed.
I have noticed in the past that some deer seem to pick up on the change in looks when I had the windows open. Since trying the blackened windows I have not had a deer give the blind the nervous looks when entering the food plot.
I have the blind opened up inside my shop to air out for a few days, then it will be ready to replace the old blind if/when needed.
I'll report back on the zipper lube success or failure after it has been out in the weather for a couple months.
