I unscrewed the top panel of the DV800 to access the tuning pots. I am a newbie and so I did some calculated risk and by trial and error as info my friends from vintage synth forum...
Warning- I do not accept any responsibilities for any mishap or loss of lives and equipment, I am not a professional, I am just documenting my findings here.
Take all precautionary measures while tuning.
I used a test pen to do my adjustment and wore rubber slippers while tuning.
I located the VCO circuit board located on the left (upper deck sounds). The right controls I tested were for the right (lower deck sounds).
Use the test pen and I tuned the 2nd, 3rd and 4th pot. I tuned taking reference from the c key of my minikorg and also with an tuning app for my ukelele on myiPhone.