[ronsch]

First of all, thanks for the information and warning. I have determined which drive is failing. If I understand you correctly, all I need to do is hook both this hard drive and the replacement one to a computer. Then, I boot up, execute the linux copy instruction and my TiVo will see the new hard drive as being the old, failing one. Is that correct? Can anyone tell me the exact line of code to enter?

That is correct. Do some research first by searching this forum and the TiVo Underground for dd_rescue. It comes on the standard Knoppix distribution and is available elsewhere.