It seems appropriate that I post this link again.
Effetto Mariposa Carogna Remover. Non-toxic, very little odor, cleans up with water, and somewhat pricey.
It's a gel that is spread over the old glue. Leave it overnight on old, fossilized glue. A couple of hours on newer glue. I clean with a green 3M scrub pad and water.
While at the site, check out their gluing tape. I used it to mount my tires on both wheelsets for the Lotus. I'm very pleased. Now I must admit I'm not an aggressive rider and all of my riding in GA is on flat terrain, so there is very little stress on the tires.