So I used to live in the EU and got used to Arexons Motorsil D silicone gasket maker, which I found to be better than normal Permatex flowable silicone because it is more durable and never falls out. It looks like this:
Not sure about its use in this situation, as I have never grown enough cojones to try it, but this is readily available at most Ace locations, so I would assume Home Depot and Lowe’s would carry it, also automotive stores like O’Reilly and AutoZone.