They go on top of the float needle seat. They aren't critical but its the last chance to stop debris that would prevent the needle from closing. If it doesn't close the engine will run rich and gas would flow into the cylinders and engine when its off.Thanks for the welcome, & I'm thrilled to receive a reply so quickly!
I'm ready to re-install the carbs, but will tear them back down if those filters are critical. Don't really want to though. raying: