Problem solved. Found the problem - thank you!

What was the problem ?

More damper woes affecting tonearm. I've managed to find a damper which is fantastic! Cannot wait to have her working again. She's all cleaned up, and all other elements are working. I've had to remove the two DIN pins though.. Beocenter trying to control Beogram using Datalink was odd: the keys on Beocenter - left and right - weren't controlling the system correctly.. And it was just behaving a little strange (suddenly the tonearm up/down key wouldn't function. Began functioning again when unplugged). Are there incompatibilities between Datalink on these two systems?

Steve wrote:

the keys on Beocenter - left and right - weren't controlling the system correctly.. And it was just behaving a little strange (suddenly the tonearm up/down key wouldn't function. Began functioning again when unplugged). Are there incompatibilities between Datalink on these two systems?

Yes, these first decks with remote control are not compatible with the Datalink, which age began a few years later. The 4004 is made to be controlled via Beomaster 2400-2, which has ultrasonic remote.

Chris