Prophet 600 Poly Mod VCO B to modulate VCO A

So, I don't like how the Prophet 600's VCO A changes in pitch (not just timbre) when using Poly Mod VCO B to modulate the pitch of VCO A even on the original factory OS. It is not a software thing, it's the hardware itself. 

The circuit that feeds VCO B's output to the CV input of VCO A is not AC coupled (it does not have a DC blocking cap). Thus a DC offset is introduced which changes the tuning of VCO A by raising the pitch. I hate this. I never use Poly Mod VCO B to modulate the pitch of VCO A. 

I held down a single note with Saw wave selected on VCO A and VCO B was zero volume. No Poly Mod.

Here I added some FM (frequency modulation) to VCO A (Saw wave) in an unmodified Prophet 600 by using Poly Mod VCO B to VCO A frequency. If you look at the fundamental, it goes up in frequency relative to the first image.

My thought were to mod the Prophet 600 to add a DC blocking cap, for example between the 4061 (e.g., U429 pin 1) and the CV in (pin 15) for VCO A (e.g., U28 CEM3340).

However, for the topside of the PCB, the traces that connect these two are pretty much inaccessible.

A much easier way of doing this was to lift one leg of R430 and add a 0.1 uf cap between that leg and the hole you lifted it out of (and R480, R429 etc. Look at the schematic in the service manual for the other ref designators).

I tried it out (adding a DC blocking capacitor) and it works great. No longer does my using VCO B to FM VCO A cause VCO A to go out of tune. 

Note, clearly this makes any preset that uses polymod B to modulate VCO A sound different. (But in tune)