The model 4000 is an RF only unit as the original post states. It does have an IR window and a place on the ciruit card for the sensor. As Mike stated, it can be upfited, in fact some kits to do it are sold on the web. The instructions on how to do it are at
[Link: carltonbale.com] if you are handy with a soldering iron. As far as the warranty issue, the 4000 is WAY out of warranty, but, beware, you could take a working unit and make it a non-working one!
I also agree with Mike that the only remote I have seen that works is the DISH one. It is about $50 retail, but can be had for less. It will work most TVs VCRs & CATV boxes, but won't work most DVD players, so it won't do what you want!
randy