Comcast red OK/Select button, about $6 on EBay. Setup code 21267

If you want a new remote and/or a retail store, get the RCA RCRP05B ($20) setup code DVD/DVR 1267.

You'll need to manually program a button to send this IR signal.
1) Assign the setup code
then
2) Press Setup until 2 blinks
3) Enter 994
4) Tap Setup
5) Enter 39101  (RC5, system 21 decimal, function 97 decimal)
6) Tap a button (for example PIP On/Off) to assign the IR signal to
The remote should blink twice.