Double check when the eos switch is active. Make sure it activates near the end of the stroke so that you aren't cutting power before the flipper has fully extended.

Was the original solenoid coil resulting in weak action also, or did this start after you rebuilt the flippers?

Some new eos switches-- you need to run a file lightly between contacts as there is a film on them.

There is a common connection after the right flipper button to the upper and lower flippers. Any issue with where they are soldered together? Was it working at one time and just started this behavior?

Is the flipper coil wired correctly? If you've got the windings backwards the weak coil will always be in the circuit and your flipper will always be weak.
Flip Flop Flipper (resized).jpg
The strong kicking coil is the upper coil in this drawing and the weak holding coil is the lower coil. You can often tell which is which on the coil by examining the thickness of the wires that come from under the wrapper and wrap around the solder lugs. The kicking coil uses much thicker wire in its windings than the holding coil.

If it's wired correctly the solder lug that has just a single thick wire disappearing below the wrapper should be connected to a black-yellow wire from the flipper button. The solder lug that has a thick wire and a thin wire should be connected to a short jumper wire to the EOS switch and the solder lug with just a single thin wire should be connected to the red wire.

/Mark

Here’s a few pics to make sure wiring is right. I just happened to have mine in the shop with the hood up!! Top pic is upper right flipper, bottom one is the right main flipper.

B328FD3A-5A60-450C-89A3-6695148F9094 (resized).jpeg

CDB5963E-B9FC-449A-B11A-7C6601B71D63 (resized).jpeg