Sorry it took me so long to get back to this.

I took my tank apart and tested it and found a link by the screw that hold the stopper together. I put in a new stopped and a new screw and still had the same leak (when under pressure). I put a bunch of sealer and glue and whatever I had to do the trick over the whole stopper assembly and screw. No leak! I felt like I genius...

I fueled it up with a brand new gallon of YS 20/20 and also a fresh O.S. "F" plug. It fired right up.

Ran PERFECTLY!

Sorry green river rc, but you're gonna have to keep that Saito!