Control Unit Problem ??

[weisach911]

I have a problem, why else would I be sending this message, but anyway, I have a 1980 911SC and it is running eratic. I've tested everything on the car and replaced alot of parts which I thought might be the problem. This is what I believe it boils down to I've connected a high-impedance (digital) dwell meter to measure the duty cycle of the CIS frequency valve and Connected the positive lead of the dwell meter to the green/white wire pin, and the ground to the brown wire pin. When the engine is at normal operating temperature, the reading on the dwell meter should dither around 45 degrees but it doesn't there is no change whatsoever in the dwell meter when I attempt to adjust the air/fuel mixture ratio on the fuel distributer. After doing some extensive research, it states that the frequency valve should make a buzzing sensation and there is none. I've purchased a new frequency valve and connected but there is no buzzing or change. The only other item I can think of would be the Oxygen Sensor Control Unit. I'd hate to dump $461.00 on this unit to determine that this did not fix the problem. Is there any way of testing the unit?? or could it be something else?? Like I had mentioned previously, there is no change in the frequency valve with the old or the new one (unless the new one is defective). Please help.