I have a Data East Hook machine. When you activate the flippers alternately it adds points to your score without the ball being in play. When the flippers are activated it changes the roll over switch lights at the top of the playfield and on the side out lanes. Does this mean that one of the diodes on these switches is bad and allowing current back through or should I be looking elsewhere? Maybe the switch matrix? Any help on where to start would be great. Oh I disconnected the diode on the right flipper coil which had been giving me trouble and it tested fine. I also replaced the rectifier on the flipper control board as the right flipper would not stay in the up position and is now working fine. The above two items were done prior to noticing the flippers adding points.

Very often if a flipper activates a score (and you can tell which score switch is being activated) you will find that another score switch is set too close and just needs to be properly adjusted.  This often happens with the switches behind rubbers or targets that get pounded a lot.

Sounds like the contacts on a playfield switch are too close together and the vibration caused by the flippers is making the switch close. I'll bet if you bang on the sides of the machine you'll find the points are added as well.

Determine how many points are being added with each flip and then find the switches on the playfield that add the same number of points. Eventually you'll find the culprit and you can adjust it accordingly.

EDIT: Wayne beat me to it...

Thanks guys you were right switch # 33 was too close and was activated in switch test when I banged on the side of the machine. Thanks again and good call.