the other day i picked up a nes very cheap. i figure it just needed the basic 72 pin connector cleaning and tweaking and it would be working fine again. now the picture on screen usually displays fine for about 1-2 seconds then kind of mess up and go black and white. i have been googling to try figuring out how to repair it but not finding much. i have narrowed it down the RF modulator in the nes because if i hook the video wire to the composite pin on the nes's main board i get a clean picture but i don't get get it at the normal composite output on the RF modulator. i have been googling trying to find a solution but not come up with much which. any help would be appreciated.