Magnovox projection tv slow tuner

I just got a 55inch Magnovox projection tv from a friend of a friend. Works grear except it's very slow to change channels. Model 55PB288, date code 9-19-01. Whe changing channels the screen will go black for 20-30 seconds before the new picture comes on. It's also slow when adjusting volume or using any of the menu functions. The closest source for service I've been able to find is over an hour away, expensive service call. I'd like to have some idea of what might be causing the problem and if it's something that I might be able to repair myself. Anybody seen this problem before?