How did you check out the remote? I usually use a video camera myself.
When you look at the remote you will see the LED flash when you press the
remote's buttons. A friend of mine once had a similar problem. He just
metered at the output of the remote and since he was getting an indication
there he said it was working. When I used my video camera and couldn't see
any flash I changed the LED. That fixed it right up.
You can get the schematic from Fisher/Sanyo. I have a Fisher CA-271
system. When I first bought it I called up the company and ordered the
schematics right from them. That was quite some time ago though so I'm not
sure what they might charge for schematics now. For starters I would just
scope the remote receiver circuit to ensure it isn't just a flakey solder
joint inside the main unit as another poster mentioned.

Cheers,
Lawrence