What SQube said - Try hair drier to (gently!!) heat around edge to start lifting. If U R not familiar with contact adhesive suggest using aerosol as gets a thin even layer - (both surfaces) then leave till touch dry (10 or so minutes) line up and leave weighted down for 12 hours Need to mask up with aerosol, but that does not take long. Assume that is a surfboard pad - a bit flimsy... (Way less effort buying new pads

and clean - wet/dry board surface.)
Cheers
AP