I bought a Fender Hot Rod Deluxe about a month ago, and I have been having some problems with it. When I play a D on the 12th Fret of on the 7th Fret of the G string I can hear a buzzing noise in the back of the amp, like something is loose and vibrating. When I play the note and put my finger on the left power amp/tube to stop the vibration, the ringing/buzzing stops. Also, after playing for 30 minutes to an hour, when I turn the amp to standby there is a loud buzz and pop and the light on top of the amp that turns on to signal that I the more drive switch is selected turns on and off. I am wondering if these things are both problems caused by the tubes, and if not then what is causing them. Any imput would be great, and if you have any questions just ask. Thanks.
check for fret buzz (see Set Up sticky in EG)
could be power tube rattle
could be a bad preamp tube
could be something else
light going on and off doesn't make sense, take it in for service

could be a bad solder joint somewhere or failing component