I would definately look into the fader switch most aftermarket installs in benzes bypass the fader. I would check to see if this is the case, it could also be that new speaker wires were run tot he speakers.

Sounds like quite a project you have endured to get back to what you had.

For the antenna, the easy way to test would be to make sure you have the right wire, make sure if the car has a dash mounted antenna switch that it is set to the up or auto position, and if that is not the case, check the antenna itself.

If the antenna is at fault it is most likely the relay unit for the antenna. or possibly the motor, and in some cases the mast is broken or the gears inside broke.

Alon

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'92 300CE - Sold
2004 C240 - 744 - C7 Wheels - Android Radio
2002 C320 - 816 - Sport Wagon - Sold
2006 E350 Wagon - 368 - Dead
2015 GL350 Bluetec - 197U