Many One-for-All remote manuals and code lists are available here:
http://www.oneforall.com/support/manual . Fill in Universal Remote Control and then the model number in the drop-down menus. Then click on the link to the manual. (It's a pdf so you'll need Adobe Reader or a similar program.) The direct link to the URC-6131N manual (English version) is
http://www.oneforall.com/uploads/support/9e15c67cf9731f8b8e9b376352f23493.pdf .
Try the following codes: 0054, 0030, 0179, 0024, 0186, 0187, 0386, 1254, 1454 for Magnavox TVs. Please note that universal remotes usually only have codes for devices released at least 6 months before the remote was programmed. If your TV is newer than your remote, you may need a newer universal remote. The URC-6131 gives it a date of Feb 2003.
I hope this helps.
Cindy Wells