I had about 3 rivets with very tiny leaks in them that I sealed with a few drops of green loctite, a syringe, and some plastic tubing:
https://drive.google.com/open?id=0B_...EdSZVpRTE1DNDg
I stuffed a small corner of a shop towel into the tube to hold the loctite near the opening of the tube.
Then I used the syringe to pull a vacuum on the head of the rivet - note that the hose is sucked up tight against the tank/rivet head. This reduces the pressure of any air pocket and allows the loctite to flow further into the joint. Quickly release the pressure. I repeated this about 5 times.
https://drive.google.com/open?id=0B_...Fhoa2VzQUo3cjg
No more leak!
Don