MKS-7 alignment shenanigans.

[ATSystems]

Greeting Rolanders! I have bounced around your threads on plenty of occasions looking for protips but I'm a new registration*, thought someone here might be able to help me out.

Many moons ago a drunken hippy knocked a lighting tree onto my MKS-7, crushing half the lid and cracking the PCB's for the PSU and mainboard. I had other toys to play with and life got in the way but I have finally applied a liberal dose of solder and epoxy to the damaged boards, short of sourcing and folding some sheet for a new lid it is alive and oscillating.

Tonight's mission was running an alignment per the service manual. I am no stranger to an oscilloscope but I am seeing some odd behaviour when trying to set the VCF resonance(s) on the module board. Long story short, the peak to peak value seems to runaway in either direction. I'm shooting for 4.8vp-p but when I hit a very specific point on the trimmer it all goes to hell.

I have a whole bunch of 80017A and MC5534A's that were given a precautionary decap and stored when the epoxy issue first reared it's head years ago, I have been focusing on bank A and having seen identical behaviour on 3 known good chip combos, some pulled from my functional Juno-106 just to be sure. I've also been able to set the VCA gain and VCF frequency and width with no issue, I'm pretty confident it's not bung modules. Does anyone have experience running alignments on this thing? (or the Juno series I guess, same/same but different) Is this expected behaviour or am I missing something? I feel like I'm trying to balance a hammer on a razor trying to set this thing.

* I can't find an introductions thread, if someone can point me that way I'm happy to spill my beans