Absent on-screen display

I have an Adcom GTP-860 processor connected to a Sony Wega 30" widescreen (16:9) via component video cables. The on-screen display is not visible on any of the TV's OR the processor's video settings (i.e. Video 1, Video 2, etc.). Any suggestions?
In my set-up (Marantz 18EX to Mitz screen) it was necessary to run an additional line - coax - between video out from Marantz to a Video in (1,2...) on the tube. Then switch to that input on the tube to see the On Screen Display.

Some OSDs are defaulted to composite output. Check the Adcom manual about this.
P13 says: In order to maximize signal quality, no Onscreen
text will appear on the component outputs. The
“video component output” jacks should be connected to
component video input on your TV.

Suggest using S video & PIP on another input to be able to use the OSD...