[1QuickS]

Each throat has a squirter with glass ball check valve and a supply check valve in the fuel bowl with a glass ball, again. Unlike the Weber carbs that depend upon all check valves to be working equally well; the Zeniths may experience one squirter not working correctly while the other two perform fine. I have serviced two sets of the Zeniths with one more on my bench at this time and have decided to stop offering service for these as I was having difficulty making the check valves work and I don't have a source for new replacements...

If the check valves cause an obvious swirling in the fuel bowl when the throttles are opened then you have a faulty check valve and you will not be able to get the squirt qty right. Also, if the o-ring on the squirter body allows fuel to bypass the seal then you will have a poor shot due to that. The check valve in the squirter keeps the fuel from draining down into the bowl so if that one is defective then the fuel will need to replenish the lost fuel in the vertical fuel supply gallery before the squirt begins.

Of course if check valves have been replaced with jets then it won't work at all as you opined.