There is always a bit of play on the flipper mechanism. I have changed the plunges, bats, coil stops and bushes for brand new. If you put the bats too deep into the mechanism it will worn out the bush and you are risking damaging the playfield. Believe me its fine.
Weakness can be caused by the EOS. As I said. File the contacts a bit or replace them.
Not sure about the error but the opto-chip is a good suspect as long as you are sure that all the tapes, ribbons are sitting properly.
The LEDs got some small wires that sometimes dont make a good contact. Remove the socket, remove the LED itself from it and bend those wires a bit outside so thay make a good contact within the black socket and then put it all back. I have also reflowed all the light PCBs so there should not be a problem with them.