You might try the link again, Tortugas. It worked for me and the pdf displayed is the same as my owner's manual, which I think you'll find less than illuminating when it comes to trouble-shooting.
It sounds to me though that you're not getting input from either your transducer or your paddlewheel; you should have both for depth and log functions. I would check the wiring, paying particular attention to the ground wire (green) to ensure there are no breaks in it.
I understand your frustration and, if it is any consolation, this is the first I've heard of Silva (whoever they are!) being involved with the instruments. I was never able in the past to find any support of them from ComNav or Nexus either and it appears that they were a short-lived product sold exclusively through West Marine and beyond that knowledge there is a wide chasm of information I'm lacking, other than that I own one and it's still working.
“Scientists are people who build the Brooklyn Bridge and then buy it.”
Wm. F. Buckley, Jr.