I went through the same exercise, including fixing the little ratchet pal on one of the number wheels. Bench tested it, and it worked fine; installed it, and it wouldn't work. Took it out again, bench-tested it again; and again, it worked. Re-installed it: same story again, wouldnt work. Pulled the cable, cable looked fine. Replaced the whole unit with one from a later model and, of course, had to get another cable because the connector wouldn't fit. All is well now, but I'm still at a loss as to why the first one behaved the way it did. I sincerely wish you more success with the repair job than I had.
Bob S.