Alpha Juno 2 VERY noisy chorus needs repair help

[trondl]

Recently i bought this unit cheap knowing a few things needed repairing.
All of them fixed easy but I created a new one:
A noisy chorus circuit!
The noise can be described as digital noise/silence shaped with a square wave 50% / 50% timeframe (drrrrrt / silence, drrrrt / silence...). The noise increases with CSR RATE, but goes away if bellow ca 50 value.

The unit is fairly clean and shows no obvious signs of shorts or defect parts.
Any help here?