You can loose 3db in signal strength in the aerial connection. Trace the path from PCB to the aerial and disconnect and clean all joints with fine grade wet and dry sandpaper and apply grease. This should get the stereo light working.
Hell, I didn't know a bad connection from the areal could make one loose 3db.
On my end I cleaned the whole thing, thinking the antenna connection had a problem somewhere between the antennas themselves and the receiver end. So I cleaned just about everything on the way, from the copper connection to the antennas (even the screws that hold those), the connector, resoldered the plug that connects the antenna wires (which I replaced, both the wires and the plug itsself), and checked the pcb for any loose tracks, loose solder,... It didn't give me any better stereo reception except for 1 Station (but that s a station I can even grab with the antennas closed and in their holders).
I only noticed the "tweaking" in the service manual afterwards.
Cleaning and. Regressing the variable resistors didn't change a thing... The only noticeable difference I got was when moving VR02 ever so slightly... And miracle : stereo recovered - but it then came with constant "hush" kindof noise till I did the same thing on VR01..
Eversince réception is excellent and I even recovered the orange colour on the led (on the dial) which only was red or green prior to the VR01 VR02 intervention.
While at it I also replaced the totally "melted", I presume rubber, band that goes from the tuning wheel to the counterweight. The smurry came off pretty easely with ispropanol alcohol. And on the bright side : I did my first replacement of the kevral wire (and little spring) ever... And quite honestly I must say I hope I won't have to do any of those again...