Just had this problem, and it turns out the plunger was worn down about 3mm or so, presumably there was not enough 'plunger' or coil force due to lack of length ot hold the flipper up - it momentarily drops down, then re-energizes.

So a new plunger fixed mine, but coil be a coil stop as well.

With WPC machines, i was led to believe that the EOS was pretty much redundant - i remember reading on pinrepair that if the flipper button is pressed and held, and the EOS is not closed in a certain number of milliseconds, then the fliptronics board drops the coil to low power to eliminate molten coil disease...or am i wrong?