Ok, we checked the wirings inside the radio module, and they look ok. Also wirings inside the empeg itself seemed ok. We cleaned empeg's back connecto to the sled, and the sled's connector too. I did not check the wiring behind the sled, though, which I am doing soon.

As a matter of fact, the radio was not working at all and this made me think the poroblem wa sin fact with the radio. Then I slided into my sled a friend's empeg and ... IT WAS WORKING! Perfectly! Notice that my friend's empeg is much harder to push into the sled.
Then, worried that it coudl be something into my empeg, I plugged it back in and the signal was there, but weak!
They I plugged my friend's empeg back in, and the signbal was gone.
Mine again, and signal still gone. Never cvame back, neither with his nor with mine.

So, I think it must be some wiring on the sled, don't you think?
Or maybe the defective radio module just happened to work again for one more time?