Look at your 00-90 unit in the head. That is usually where the alternating occurs as you score points. There is a switch blade that is triggered by the plastic cam. This switch turns your alternator relay on and off.
I have had that switch come just a bit loose on a game.
Also, check and clean the contacts on that switch. It gets a lot of use.
Move this to the EM sub-group if that doesn't fix it.