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. Using a short patch cable, patch the #2 Input of the Normal channel into the #1 Input of the Vibrato channel.
2. Plug you guitar into the #1 Input of the Normal Channel.
3. The Volume and Tone knobs on both the Normal and the Vibrato channel will now effect your sound. So turn down the Normal channel and adjust the Vibrato Channel Tone and Volume first. Then bring up & adjust the Normal channel Volume and Tone. (If you experience any feedback while doing this, remember that the Vibrato channel is voiced a little brighter than the Normal channel. Lowering the treble and volume on the Vibrato channel a little will reduce any feedback).