Hopefully you are using the
+48v 3.2A SMP supply (Switch Mode Power).
for the flippers.
Is 3.2 amps enough? I believe the one i"m using is 7amps. (probably but too lazt to look up)
Make sure the neg is wired.
Mine has tested fine with a simple switch Mosfet set up, aurdino and some resistors.
All the best,
Red