Please help me fix my Multivox Jazz Flanger from the 70's

[Zero]

If I were you, I'd do two things. First, what's that clock frequency, calculated as 1/period? And can your o'scope see that high a frequency OK? Are you using a 1:1 scope probe or a 10:1 probe? All this is just to filter out measurement error before we go hunting for ghosts. Try calibrating your probe on the scope's calibrator.

I'm using a 10:1 probe and the oscilloscope (an old Telequipment) is designed for TV repair/diagnose.. so it should at least get me into the MHz range.
The period (at the lowest speed setting) is somewhere around 15 microseconds, which would correspond to f = 66 kHz. That's just more or less, though.. but at least we know the range.

Can you breadboard a simple three-inverter CMOS oscillator and feed the output of that into the clock input?

I was just about to ask if you knew a simple circuit that would produce some kind of square signal...   
I googled around and found a nice app note from Fairchild Semi.. I'll try that out later this week -- I'll keep you posted.

[cjlectronics]

It is possible that the BBD is sucking the life out of your clock signal. You can check this by cutting the clock signal trace at the BBD.  If the clock signal squares up and the peak voltage increases the BBD could be bad.  You can use an R5106 but I beleive you'll have to limit the p-p signal into the 5106.  Mark Hammer has the specs on the 512 and the 5106.

[the_ms]

I'm using a 10:1 probe and the oscilloscope (an old Telequipment) is designed for TV repair/diagnose.. so it should at least get me into the MHz range.
The period (at the lowest speed setting) is somewhere around 15 microseconds, which would correspond to f = 66 kHz. That's just more or less, though.. but at least we know the range.

Don't you use my Tektronix probe?
That one is a simple 1:1 probe. On the right side of the vertical deflection unit is a switch to adjust the gain for using a 10:1 probe. It should be in the correct position to allow to measure the voltage on the screen.

The bandwidth depends on the type of plug-in unit (vertical deflection amplifier) and the gain. The 10:1 preamplifier decreases the gain drastically.
Here are the 3dB bandwidth values for 1:1 (and 10:1) (Telequipment type 43 scope)

Type A:       15 MHz (800 kHz)
Type B:       75 kHz  ( - )
Type C:       15 MHz (800 kHz, 75 kHz for 100:1)
Type G:       10 MHz (500 kHz)
Type H:       25 MHz (5 MHz)