Series 2 Tivo dead hard drive

Hi all. My Series 2 Tivo's hard drive just died. It is an 80Gb unit I got back in 2006 with lifetime service. Sure got a good run out of it. I'm comfortable with coming up with a new drive and using MFS tools on it; can anyone help me find a backup image of the OS? Model number is TCD540080.
TIA,
Brian