And here’s the response from Percolator designer Brach Seimens:
“Yes, your meter should read continuity across the output jack terminals when the transformer is connected. It’s actually not making a short, but your meter will tell you that it is (when it’s on the continuity setting) because the resistance of the secondary of the output transformer is so low. On the resistance setting you should see a few ohms across the output jack terminals.
I’m glad you are enjoying the build!
-Brach