Another technique I have used is to take another piece of tape, such as duct tape if you don't have any of the original tape, cut off a piece about 12" long and tape the ends of the tape together to form a loop (sticky side on the outside of the loop). Spray some of the Goof Off, or 3M, which ever you prefer, to the surface. Let it set a minute or so to soften up the adhesive, then try to lift off the old adhesive by sticking the sticky side of the loop of tape to the adhesive and with a quick lifting-up action, lift the tape up off of the adhesive repeatedly. Keep sticking the tape to the adhesive and lifting it up and little by little the adhesive sticks to the tape and comes off. That is just one technique I have used that has worked in the past on other types of adhesive. May work, may not, but worth a try.