I am working on a Stern Hot Hand that has a Two Bits MPU in it. Problem is limited to MPU as I have swapped out the MPU and the problem goes away. Unfortunately I don't have another MPU laying around so... I have checked all the components around the 555 for the Display Interrupt and they all seem to test good. I have swapped out the 555 chip and changed the resistor at R21 to 33K. Nothing has changed... Suggestions? Thanks all.