Did you check the flipper button cabinet switches. They must be new "tungsten style switches"? or at minimum clean to get a consistent flip. I find that you often need to use a small file on those tungsten contacts to get them shiny and making nice contact. SAME is true for the EOS switches. Tungsten switches are not like a typical pinball switch (which you should never sand or file down). With tungsten switches, sometimes you will need to get aggressive.

From the top of the PF, can you slightly lift up the flipper bat and push it back down? It should have about a washers thickness of up and down play through the PF there or you will get some very weak flipper power. Also known as "backlash", play, or slop. It is a good thing in this case! It's the #1 reason I see when encountering a slugging flipper and no one ever talks about it. Both flippers should have a similar amount of play. If not, loosen the flipper bat shaft, lift it up a bit, then realign and re-tighten it.