I used Gorilla glue for the velcro strips on a pair of Sophia speakers that had a similar issue. It worked fine. I also recommend leaving the grills off, or call Wilson audio for help as recommended.
The grills and adhesive deteriorate over time. My mother in law has a pair of cubs. I noticed the grills were looking old and tired, so I ordered a new set from Wilson. Cheap price, installed nicely.
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