Weak flippers are usually the result of a worn EOS switch or a faulty solenoid.

The EOS switch contacts need to be totally smooth with no pitting. If they are pitted, the contacts and/or switches will need to be replaced. You can also check the flipper button switches to see if they are clean.

Check the resistance of the solenoids with a multi-meter.

The solder joints on the solenoid lugs look suspicious. You might want to re-solder the wires to the solenoid lugs.

Interesting to see the label above the flipper assemblies that says to use 29-400 / 22-400 coils. Solenoids/coils installed for the flippers are labeled 28-400. Also, the paper wrapping on the flipper solenoids looks like they are from a Williams machine. But, a lot of solenoids and coils are interchangeable between manufacturers...

Also, make sure the EOS switches only open when the flippers reach the furthest "up" position. If the the EOS switches open before the flippers reach the furthest position of travel, the flipper coils / solenoids will become extremely weak...