I agree, if the handshake issue is with a cable box only then the move to component makes sense. I had to hook up my sister's system in this manner, everything now works great.
You might possibly benefit from checking with Marantz on it's firmware, you might need to send the 6003 in for service and a firmware upgrade to the latest sversion they have for it, if theyu have made any changes. But judging by this bit of info I found on their web site, I think they are not in the habit of adjusting their firmware.
"Assuming everything in your system has been connected and assigned correctly, the first thing that can be tried is to factory reset the set top box. You may need assistance from the manufacturer of the set top box to do this if it is not outlined in the instruction manual. This would also require you to readjust any of the settings as necessary for your system requirements. If this does not clear the problem, then power down the display and the receiver. Reset the set top box once again and then power it off. Then turn the display on first, then the A/V receiver and then the set top box. The reason for this procedure is to force the set top box to reinitiate the HDMI 'handshake' protocol as in many cases it was connected to a display directly and memorized the display's handshake protocol which of course is different from a receiver's handshake protocol. This generally works for later vintage set top boxes.
If not, you may need a firmware upgrade to the box so it will 'handshake' with an HDMI repeating device (your receiver). To do this you will need to call the service provider and ask them to send the update to the box. This update is called a "repeater flag firmware update." This can usually can be done through the phone/cable/satellite feed while you are on the phone. If you are still unable to get your HDMI to operate properly, as an alternative, connecting directly to the receiver using component video cables, and a digital optical or coaxial cable, can provide you with similar video and audio quality. Many current model receivers video up convert component video to HDMI video so your existing HDMI connection to your display should not have to be changed. The receiver's instruction manual will tell you if this video up convert feature is available."
