Tamara also emailed me about this. I've sent her off looking for the model number. As the receiver dates from around 1992, I'm hoping that there's a code for it in my old Radio Shack 15-1905 remote, the reason being that Radio Shack actually lists all of their own model numbers next to the appropiate setup code.

Once we know the right setup code, then it's just a question of figuring out which current remotes have the code, or loading it into a new remote.