Per Van's instructions, using green loctite, I created a little pool of loctite around the leak using clay. Then I used a hand pump to create about a 1 psi vacuum. After a couple minutes, the manometer appears to be holding steady. I am going to leave this setup as overnight to let the loctite seep and harden.
I brought the other fuel tank that I was able to plug with proseal back into the house to warm up so that I can start testing it tomorrow.