create small basins of folded tape around the suspected parts. (also around the handle and fin boxes) pour some soapy water (water + some drops of dishwashing soap) in the basins put the board in the sun 2mn
Do not leave in the sun more than 5mn. If there is a leak, it will bubble in the first minute.
How good were these repairs and who did them? I’d suggest if a repair was so poorly done as to let water in you’d see it. I’d check fin boxes and handle first plus all leash plugs leak just by virtue of their design so if not put in properly in a styro board you’re asking for trouble.
where are u? I think WA right….? If so come in and see me