Hey... This is a little labor intensive, but it's a VERY nice mod for the champ. It knocks the champ's minimal yet normal background hum down to nothing!
 
Here are the directions for doing this mod on the Vibrochamp or regular Champ.
 
1. Remove the pin #9 grounds of each 12AX7 preamp tube and remove the pin #7 ground on the 6V6 Power tube.
 
NOTE: Go ahead and get rid if the ground pad of solder for each of these connections as well.
 
4. Remove the single strand of heater wire (usually green) from pins #4/5 on each preamp tube and on pin #2 of the power tube. Follow it back to the pilot light and remove it there too.
 
5. Remove the #1 green wire from the power transformer from the other side of the pilot light.
 
6. Find the 'other' #2 green wire that 's bundled with the power transformer ground wires. Remove this from that ground pad and resolder your power transformer grounds if necessary.
 
NOTE: You may need to extend the length of the green power transformer wire you just removed from the ground bundle to make it reach the pilot lamp. Do this with a matching gauge of wire.
 
7. Solder two 100 ohm resistors from the pilot (one on each leg), to their own ground pad on the chassis or on a transformer bolt, (whichever you prefer).
 
8. Take both of the green wires you have from the power transformer and connect each one to it's own leg of the pilot light. 
 
Now, the fun part....
 
9. Solder a wire that is at least the same gauge as the heater wire you removed earlier to each lead of the pilot light. Twist those two strands until you have enough wire to go to the 6V6 power tube, where you're going to attach one to pin #7 and the other on pin #2.
 
NOTE: Heater wiring should be far enough above the tube socket so that it isn't touching any wiring below, but low enough that it doesn't extend above the plane of the chassis and snag during insertion and removal.
 
10. Continue this twisted wiring method connecting pin #7 of the power tube to pin #9 of each preamp tube. And connect pin #2 of the power tube to each preamp pin #4/5.
 
NOTE: The "rectifier" doesn't need a heater wire connection.
 
After completing this, as always, double check your work before powering up. If you did everything correctly, then you should be rewarded with a Champ that has a greatly reduced or eliminated background noise/hum.
 
Enjoy !