I have heard also that but a lot of people talk about trying to fix heat isssues when they get the 3 red lights. I ask the guy how he knew the drive was not bad and here was the reply I got:
"The xbox was still functioning once in a while, the dvd drive didn't have any problems when system booted up. The heat gun fix was attempted on the 360 and worked for a couple days. It was the video gpu solder points that went bad in the xbox."