Ive done this many times and i cant stress enough, You do NOT want to leave that old cover under there, what you want to do is just take the seat off the bike and turn it over and remove any thing blocking access to the staples that hold the cover on, Then you take a small screwdriver/pocket knife or an actual staple remover if you have one, then you simply remove all the staples and the old cover, then use your old cover to get a rough cut out of the new material for the new cover, leave at least 2 inches extra all the way around the cover until your totally done stapling it then go around and trim off the extra, that way you are always sure not to remove to much material from your new cover.. as far as the spray glue, you can use any brand, 3m/loctite/elmers brands of spray glue made for vinyl will work fine, make sure you spray just a light coat on both the cushion foam and the underside of your new cover, do NOT use too much because it can soak through and stain your material, ive done it before! Then another tip is, after you spray the glue, let it tack up for like 2 full min so the solvent can evaporate a bit then press on your material starting from the center of the seat and work your way out to the sides.. And another important thing is to take one of your staples out and make sure you buy the same size staples to redo them, and also make sure you buy the marine grade "nickel" staples because they will never rust, the regular staples will rust instantly if they get wet...Good luck! and feel free to PM me if you have any questions about the process..