I have a 7" Sony SSM-721AMR back-up monitor. It has obviously been wet in its earlier life. I repaired the power cable, hooked it up and tested it with this result:

The CRT illuminates, the camera transmits sound, the volume control works, the brightness control works, the contrast control has no effect on the illuminated screen, and there's no picture.

How can I test the camera and monitor separately to determine which, or perhaps both are faulty?

Any suggestions as to whether I should try to have it repaired, or scrap it and start over?

If repair, where? No local shop wants to even look at it.

Any other advice?

I would try to hook up a VCR or DVD player to the monitor screen to see if that works. If so, then it's the camera that's bad.