Speaker magnet glue

[esl 63]

Depending on what surface you have you can use a primer.
polyethylene, polypropylene, polytetrafluoroethylene (PTFE) and thermoplastic rubber shall have SF 770 treatment before glue.
Metal : Metal Primer EC-3901 from 3M

 

[Earths]

Find a country that has an accessible tech line and call 3M, they're range is massive along with their R&D