MS-20 filter stripboard troubleshooting

You could try building the simple VCA from the lm13700 data sheet: @analogoutput beat me to it

But… if there’s nothing across the resistors, the next thing to check is the transistors that do the CV to current conversion. The more I look at the stripboard in the original post the more confused I get about that part of the circuit though so I’m afraid I haven’t much to suggest. Looks like a kind of current mirror but it’s confusing.