Amplifiers contain voltages high enough to Kill you even after the amp has been powered Off !!! If you don't have enough electronic experience to identify and discharge the Filter Capacitors which contain these Deadly voltages, take your amp to a Qualified tech. If you don't know a qualified tech in your area, post a request in the alt.guitar.amps newsgroup, the folks there will be happy to help you.
1. On the first 12AX7 preamp tube, Jump pins 1 to 6, 2 to 7, & 3 to 8.
2. Wire a 100K resistor to Pin#1 (plate).
3. Wire a 3.3K resistor with a 25uf 25volt cap across the resistor, to pin #3 (cathode)
2. From the channel's "hot" side of the input jack, wire a 68K resistor to pin #2. (grid).