Noise Toaster VCF Issue

[mecha-cat-zilla]

Hello. Long time observer of this forum & after 5 days of troubleshooting finally holding my hands up to needing help so registered.

This is my 2nd synth project so still very new to electronics/DIY etc. So, the issue I'm having is with the voltage controlled filter on the Noise Toaster. After a lot of trouble shooting I seem to of narrowed the problem down to the VCF mod (components Q8, R40, R45, R39 & R44). Basically, the filter doesn't work as it should. When turned fully clockwise it's open as it should be, but when turning it down it just steps down slightly from fully open & remains like that for the remainder of the pot turn rather than giving a full sweep (if that makes sense). When Q8 is removed (thus isolating that part of the circuit) the filter works exactly as it should giving a full sweep of the filter range.
Now, findings with Q8 reinstalled:

*When a mod source is added from switch S6 it modulates as it should with R38 turned fully clockwise. Turning R38 counter-clockwise eventually brings the filter back to being slightly closed as with no modulation source.
*Swapping out Q8 with another from the board (I only had enough for this build so no spares) yields the same result.
*Disconnecting R38 gives no change in the way it behaves minus being unable to modulate the frequency.

The only thing that has bought me close to it behaving as it should is removing R44 (100K to positive). This makes the filter behave as it should but doesn't give me the full frequency range of the modulation sources (apart from the LFO square wave I just get a "click" for the waveform modulating). I tried replacing R44 with different values but to no avail. So, my question is, what the hell is going on? Any idea? Can there be manufacturing differences in parts depending on brand? I've ordered some more 2N5457 JFET's to replace it with (produced by Fairchild as used in the kits provided from the MFOS site rather than Nat. Sem. that I have here). I've gone over it so many times I can't see any issues & feel I've exhausted every option, but maybe I'm misunderstanding something? I've attached my stripboard layout for your perusal (& a link to the schematics if needed: http://musicfromouterspace.com/forums.html?MAINTAB=SYNTHDIY&PROJARG=NOISETOASTER/NOISETOASTER.php&VPW=1670&VPH=785 ).
I hope someone who knows a lot more than I do can help me with this as slamming my head against a wall isn't fun anymore.
Thanks for your time.

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[mecha-cat-zilla]

Rather predictable that as soon as I ask for help I finally figure it out. Turns out the mod pot had a bad pin so wasn't receiving the negative supply it needed to function properly. Hopefully this will help anyone who happens to have a similar experience. Thanks

[blue hell]

Glad you found it

And

[wackelpeter]

Fine that you figured it out.

And a happy welcome from me too!