The VERTICAL POSITIONING pot looks to have been completely, and very cleanly removed. The violet striped, red striped, and black orange brown striped wires that (I assume) went to the pot were cut pretty close to the DC BAL pot and neatly tucked away.
FWIW the s/n of this unit is 002835 and on the backside of the front faceplate is written RCA 3374.
rivet_head