Under bonnet foam insulation

[M6luvva]

I have the remnants of this still stuck to the underside of my bonnet. I read in a previous post that Toyota brake cleaner did an Ok job of removing the residue /glue. After 2 hours of scrubbing my fingers are red raw and I have only just cleaned off one of the 3 panels.
Is there a better way? Someone please put me out of my misery....

[Awarded]

I used Autoglym tar remover. It did take a while but worked. Possibly using a soft plastic scorer would help? As long as your careful.