No record on a Umatic

[RJMiranda]

Sorry to suggest it... but maybe the input select switch is in DUB. Audio connectors work the same for both LINE and DUB inputs. If this is not the case, check the video level meter. If it reads in the blue zone but you don´t get the video recorded, there is something wrong with the video modulator or record amplifier circuit.
The Sony 5000, 7000, 9000 series UMatics employ solid-state mode switching. Maybe a faulty transistor is keeping the recording signal path grounded. Time to get a service manual.