You have checked that it works manually so I would agree this sounds like a connection problem. Listen for a motor noise when radio turned on or off. Or reopen case and see if it turns, see if connection fails somewhere. This could be caused by bind in mast or gears. You may have allready done this, if so check/ clean connections. A clean mast moves very freely. good luck.

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Delsman
92' 400E, 107k
BMW 535i, 165k