If your problem is heat related and you don't want to open the case, then here are a few other ideas for keeping it cool without opening the unit.
1). If you have the vertical headroom, extend the length of the feet by placing a "twist-off" soda bottle cap ( or something similar - Lego block for instance) under each foot. This will give more room for cool air to be sucked in from the ventilation holes on the bottom.
2). Turn the 5005 off when it is not necessary for it to be on. Leaving in on 24/7 so you can record at any given moment only wastes electricity and generates heat. Obviously if you use the 5005 tuner to watch TV or pass your cable signal through the 5005 to get to the TV, the 5005 must be on when your TV is on.
3). Do not run the 5005 in an enclosed entertainment unit. At least have any doors open when the 5005 is in use.
4). In an enclosed unit you can mount a small exhaust fan to the back of the unit itself. Picture the fans used to exhaust air out the back of PCs. Obviously you would need to find one that meets your voltage requirements. I'm sure Radio Shack has several.
The easiest thing to do that has helped many in this forum is to open the case and rest the case back down on the screws which have been partially driven back into the chassis. This provides significantly greater ventilation, protects the 5005 from something falling in it and allows you easy access to inside the case if you want to add heatsinks or gather information.