Second on replacing the batteries. It's doubtful they are still good enough to give full reliability.

Hey Oberst, which cell phones operate on 72mhz? I've never seen one of heard of one, nor are there any in development. You might need to check the facts on your conspiracy theories a little closer.

2.4ghz was developed because the market wanted interference free radios that didn't require frequency control. It hasn't been a perfect transition like everyone hoped, but the bugs are pretty much worked out now. Side benefits are shorter antennas, quicker response times, lighter and more durable electronics, telemetry ability, and (beginning just recently) cheaper systems. There is nothing "wrong" with the old technology as long as the equipment is in good condition. But the market is moving to the new 2.4ghz because it does solve the problems that it was developed to solve and it works.