When heat fails, and I agree that heat is the first choice, then it's time for other stuff!

If heat removes most of the tape, but leaves some adhesive residue, first thing to try is more tape! Wrap duct or other strong bonding tape, adhesive side out around your fingers and apply it directly to the tape residue. Push down and then pull straight up, repeat rapidly. This will often cleanly remove the residue a chunkj at a time.

Make a scraper that is ideally softer than the surface to be scraped so as to avoid damage. In this case you might try making scrapers out of Plexiglas or a bit of hardwood shaped on a grinder. The hardwood will "burn" end-grain while grinding and this makes it even more durable. Wrap some tape around the scraper for a handle. Next apply a suitable solvent, as suggested in previous posts, to soften adhesive. Use scraper and rags or paper towels to remove goop scraped up so it doesn't smear and/or re-attach.

The very worst kind of tape to remove I've run into has been some clear tape used to afix a yaw string. UV degrades the plastic tape so it is not mechanically strong enough to peel off, while it still protects the underlying concrete hard adhesive from whatever solvent one is brave enough to try using to soften it! I'm only brave enough to try denatured alcohol sparingly, as many solvents will instantly or later on damage the plexi.

The best approach I've found is to soak a small bit of cloth with the alcohol and apply it to the surface to soften it some. Remove, scrape with thumbnail carefully, reapply cloth. 45 minutes later the result was tape removed, sore fingernails, and minor scratches to buff out.

Shameless ad department: This never happens with a MKIV yaw string. When time comes to replace, the yaw string base peels cleanly off the canopy. Also much nicer looking than tape and yarn. MKIV and Quiet Vent is carried by Cumulus Soaring, Williams Soaring, and SoaringNV

bumper