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 tubes with a good set of NOS ones. The originals came with RCA>/b>tubes and these are great to use in the reissues. The tube compliment is one 6K6, one 12AT7, and one 12AX7.
2. Take the Circuit card out of the reverb unit.
3. Locate capacitor C10 underneath the mix pot on the circuit board. (It's obvious when you look for it). Change this cap to a ceramic disc 1Kv 390pf capacitor. This change will increase the amount of low end response you'll hear from your amp.