Radio /cd Help

Hello. 2003 Passat GLX 4 motion.V-6 Bought car with 105 k have been doing some maintenance to the car.
So far, oil, air and cabin Filters spark plugs, still need to do coolant and trans flush.
Fixed seat heater on passenger seat by replacing heater switch. Fixed check engine light by replacing evap solenoid on intake manifold .
Finally the reason for this thread is that this car has the monsoon radio cassette CD player,
It is missing 1 knob in the center of the head unit. Does any one have 1 knob off a dead Unit?
Also I have acquired a VW 6 cd player and went to the trunk and found the first aid cover and removed it. The cd player fits in the center shelf . But my question is, where is the plug located that the cd player plugs into? I felt behind and to the sides of the shelf and there is a drain line but don't see any other wires to plug the cd player into. Thanks