2. Check board to board connectors. A loose connector situation can cause instability.
3. Probably the DAC makes the noise, "pacman" like sound -> instabile CV to oscillators. Check if all 4 oscillators involved in the issue or just one.
4. Maybe a bad cap-polarity? Double check your recapping work.
5. Recapping makes sense in my opinion. I recapped the power supply and the vcf+vca board in my MP. Electrolytic capacitors have a 2000-3000 hour lifetime before they go out of specification. Out of spec means they do their jobs less and less effectively, sound becomes degraded and noisy over years.
Laszlo