Toshiba DR4 DVD- No Line 1 Input

Toshiba DR-4 DVD player/recorder. When 'line 1' input selected, 'L1 Stereo' appears on the OSD. But no video or audio output to TV. Also, "Menu" doesn't appear on OSD from RF output, only from RCA Composite output. L2 and RF input OK, and all other functions OK. Cable swaps; no joy. Could this be software problem, or more likely damaged input? Haven't opened it up yet to scope the video path from L1 port. Thanks JR