When dealing with aging synthetic rubbers and the like: plasticizer outgassing/migration. One might say that all plastics are 'moving' in this fashion (like glass not being a solid but a slow moving fluid), and the best alter/change state very slowly.
Surface needs to be soaked then scrubbed with an aggressive volatile. In order to get the placicizer off the surface and leeched out of the surface of the material.
Then a glue or adhesive may work again. for a while. Maybe. Depends if the surface goes to powder or how long it takes for further degradation via further plasticizer migration.
Some aerosol based contact cleaners have aggressive enough volatiles in them. But they can also tear down other things, in an unwanted fashion, at the same time. Be careful. Small test areas, etc.
