Bill - Today brought out an old rca tv but couldn't figure out the code problem either. I kept searching and came across a second manual for the same or appearing to be the same comcast custom dvr 3 device remote. The first one took 5-digit codes, and the second one took 4-digit codes. The 4-digit code worked for me. Here's the link for 4-digit: [Link: scribd.com]
Hopefully this will help.
-Sage