I have a Shadow that was having some reset issues, and after a lot of board swapping and plug checking i have sorted that out, however now all 3 flippers and the magnet are quite weak. The flippers are all free, with no binding anywhere. There is 76V at all lugs of all coils on the machine. So i don't know where to go next - i also swapped fliptronics boards with a known working one and still the flippers are weak. The magnet will grab the ball, but does not have power to throw it - previously is worked fine.

Any idea what would cause this sort of issue? I would normally go a rebuild all the flippers (they were nice and very strong a few weeks ago before the resets started occurring), but the fact that the magnet doesn't have strength to throw the ball leads me to think its definitely an electronic issue and not mechanical.

Yep, have cleaned all optos.

I also just did the 'flipper coil' test and they are weak then as well, so that eliminates an opto problem i would have thought (as i believe the test drives the coils directly, not from the flipper switch). Also double checked all plugs going to fliptronics board, and double checked there is no mechanical binding on any flippers - they all move very freely and the EOS only activates right at the end of the stroke.

I think you are on the right track..... Looking at the schematic, the magnet (and single drop) are driven from the fliptronics board, so it is too much of a coincidence that the magnet is weak along with all flippers.

So i tried another known good fliptronics board for good measure, same thing - all weak flippers. I also double checked this by using the Shadow fliptronics board in BSD, and it plays perfectly.

So in my mind, it has something to do with power or ground coming in or out of the fliptronics board. I have pushed the wires firmly into the IDC connectors with a flat blade screwdriver, so i guess the next step is putting new plugs on some connectors at the fliptronics board?