Different types of capacitors should not affect the range if they work properly with the power supply. However, if they _don't_ really work properly, the input voltage will vary, and thus the range can vary.

If you have to replace the capacitors, make sure their DC ratings are well in excess of the factory caps. The problem these things have is that, with stock parts, the DC load is too much for the caps in the closed environment of the case (you need to derate capacitors like this in hot environments), so they break down. The characteristic snapping or popping sound for failed caps is actually little arcs within them-not a good thing at all.

Personally, I'd leave the case off and let the poor thing stay as cool as possible.