I was the one who originally asked the question and I ended up making the change. I found some problems in my servo extensions (cracked insulators around the wires in places) and replaced all of those. Almost all the interference went away but there were still random glitches that occasionally occurred for no apparent reason. I also found a crack in the insulation of the receiver antenna. I taped that up but it didn't seem to help.

I bought a 2.4 GHz Futaba 7C and since then things are rock solid. I'm not sure if the problem is being masked or if there was possibly a problem with the old 72 MHz receiver, which was about 2 years old (Futaba 7 channel dual conversion). I have flown the plane several times since the conversion and have been ecstatic with the performance. I finally have confidence in this plane not losing control due to servo glitches.

Gary