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. Replace the stock Ceramic 0.02uF Coupling Cap in the Vibrato channel's second gain stage with a Polypropylene or Polystyrene cap of the same value.
2. Replace the stock Ceramic Coupling Cap at the Phase Inverter's Input with a 0.001uF Polypropylene, Polystyrene, or Mylar cap. Let your ears be the judge as to which composition you like best.
3. Replace the 10pF Ceramic Cap that parallels the reverb/dry mix 3.3M resistor in the output of the Vibrato preamp's third gain stage, with a Silver Mica Cap.
4. Add a second 820 ohm resistor to the existing 820 ohm power amp feedback loop resistor to increase the power amp's gain. This smooths the transition from clean to overdriven tones.