Hi Wayne, great to hear from you and good morning from Austin.
Yep that is 100% how I had been approaching with Teflon tape but this time it was really fighting back. These smaller Empire tanks/sight glass don't give much room to work around the tape. I am pretty sure if I kept at it the little bugger would have sealed. I was just looking for something with less stress LOL I think some of the problem is the sight glass is a bit short, as it allows a gap for the Teflon to get inside and block the water.
Not sure if the Amazon Silicon 3/16" ID x 5/16" OD tube will work but if not, I can get from Granger 3/16" ID x 1/4" OD silicone tubing. Even then I'll likely wrap a bit of teflon around to make it bullet proof.
Right now the Lowe's ID .170" and OD 1/4" Vinyl is holding, which bridges the gap too.