ORIGINAL: piper_chuck
Edit: forgot to mention, it's also been mentioned several times that hobby shop owners, who DID know better STILL advised customers to change them on their own.
Yes, Chuck, trying to sell the radio which is on a different channel than the buyer already uses - they're concerned about their profit ONLY not about the buyer and other RC-ers who may suffer the consequences.
BTW a radio which is not retuned after a crystal change may shoot down a plane using an adjacent frequency channel while flying perfectly fine the plane on the same channel.