Finally got the receiver running!

The TCS set is finally working. It turned out to be something stupid. Nowhere in the net or in the manual does it sat that the transmitter has to be plugged into the power supply in order to operate the receiver. Apparently there are jumpers and a relay that enable the receiver when the transmitter is plugged in.
Finally! I've been banging my head on the wall for a week on this issue. The clue was when I turned on the parts receiver with all good tubes and I got the exact same symptoms. That told me it was most likely something to do with the power supply...