Does anybody remember the specifics of the S2 sound problems (kazoo?) from days of yore? My searching fails today. Basically... I got a 540040 S2 second hand (now lifetime). It had issues with weird static/chirps in the sound recording or output. At the time it was suggested that there were some S2s with a defective chip causing the problem. The work around suggested was to make the Tivo hotter on the inside. I accomplished this by putting duct tape over half of the fan grate. So for the past three years my Tivo is chirp free but running at 48c according to the temp sensor. This can't be good for the HD or power supply caps. I would like to get another 540xxx tivo and swap boards (yes I know I will have to swap the crypto chip also). So that brings me to my question: Does anyone remember if the chirping problem on 540xxx S2s was widespread? Is there any known serial number or production date ranges to avoid when shopping for a donor unit?