It doesn’t take a lot of pressure to unseat those picnic taps. You can try shimming or stretching the spring a bit for a bit more seat pressure, maybe that’ll help. I actually sanded a bit off the top of the valve body (the smooth area above the threads where the top screws on) by laying a sheet of sandpaper on a flat surface and using it to sand the rim down about a millimeter or so by swiping the valve body back and forth over the paper. This will compress the spring and produce more seat pressure. It made quite a difference for me. My picnic taps will now reliably handle about 25 psi or so now, whereas before 8-10 psi was about it.