TECH: Ms. Pac Man reset problem

My Ms. Pac has a problem. The screen comes up as mostly dots. No sound, no
gameplay.

What I've measured:
   4.93 volts on the TTL chips on the mainboard (slightly less on the aux board
~4.91V)
   Reset line on CPU (Pin 26) is normally high... SW1 has no effect on CPU Pin
26
   Pushing SW1 causes Pin 9 @ 9C to go low
   Pushing SW1 has no effect on Pin 15 @ 9C (it's LOW no matter what)

   9C (74161) Measurements
      Pin 1 - changing state ( .466 Mhz )
      Pin 2 - changing state (varying frequency)
      Pins 3, 4, 5, 6 - high
      Pin 7 - changing state (1.5 - 3Mhz)
      Pin 8 - low
      Pin 9 - high
      Pin 10 - high
      Pin 11, 12, 13, 14, 15 - low
      Pin 16 - high

I've narrowed the problem down to 9C or one of it's inputs (I think). I'm
hoping someone with more knowledge and experience will comment on the above.
Pin 2 @ 9C's input seems very strange to me.

Thank you very much.

Below I've included pinout of the 74161 chip.

74161, 40161
4-bit synchronous binary counter with load, asynchronous reset, and ripple
carry output.

        +----------+
/RST |1 +--+ 16| VCC
 CLK|2 15| RCO
    P0 |3 14| Q0
    P1 |4 74 13| Q1
    P2 |5 161 12| Q2
    P3 |6 11| Q3
 ENP |7 10| ENT
GND |8 9| /LOAD
        +----------+

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Received on Sat Mar 17 19:30:39 2001