Quoted from ls1chris:
beside the flipper mech for the munchkin PF there is a light board that almost touches that assembly. i added a rubber oring as an insulator and reseated the connector as i had the same issue. put in led test mode, lift the PF and start wiggling the connectors if that area you will find it pretty quick. you can also mash the flipper buttons also to help localize where it is.
I just got mine. I noticed the same thing with the Monkey... doesn't work all the time. What was your solution?