I installed the valve seat with the ridged side facing the carb and the flat side facing the needle.
Ohh I didn't know that was the distinction when testing. I wish there was more written about this.
I did use an oem seat & needle however.
Engine model:123K02-0193-E1
Primer button type carb
I've replaced the float, needle valve, and the needle valve seat using all B&S genuine parts. From bench testing everything looks great; I test that everything seals right on the bench by turning the carb upside down and drawing a 5psi vacuum...