Hi
I have tried numerous methods on various items that needed glue removal over the years.
Petrol is good if you dab it on with cotton wool, it dissolves the glue and should leave the transfer.
Or, lightly heat the pad from underneath where the glue is - hairdryer, hot air gun etc, and use white clean kithen roll to dab off the glue on the other side.
It's best to take your time, and if need be do it more than once.
J.