I believe your troubles have to do with not using a solvent that will dissolve the adhesive.
Goo-Gone and Goof-Off are not the same product!
Goof-Off is pretty good for most things.
I know some people will not appreciate my next comment, but here goes!
Isopropyl alcohol In my opinion will not clean much of anything other than removing the
oils that your hands leave behind when touching the build plate.
Rubbing Alcohol will do the same.
While Alcohol solvents are quite safe and smell pretty good to, they are normally not a Solvent of
the adhesive you are attempting to remove.
What I do is:
If base is glass or metal, I 1st try Lacquer thinner -
Lacquer thinner contains acetone and other nasty chemicals that evaporate and leave the surface clean,
dissolves most adhesives with good success.
My 2nd go to solvent is Mineral Spirits.
Mineral Spirits is also nasty and does not smell very good.
If the adhesive you are trying to remove will dissolve with Mineral Spirits that would be what I would use.
You need to be careful when using Lacquer Thinner, Mineral Spirits or other nasty solvents because the liquid molecules are very
small and you can absorb them through the skin in your hands.
I tend to wear rubber gloves when using these nasty solvents.
I hope this helps you in some manner!