After many years the springs in a Reverb tank can sag, particularly the long 14″ tanks. This sagging actually changes the tone of the tank making the reverb tone a little dark and muddy. The sagging also adds to the “sproingy” sound and the reverb effect loses some of its “lushness”. There is an easy fix for this. First, remove the reverb tank from the bottom of your amp. You probably have to take off the lower back panel to do this. Usually the reverb tank is in a heavy vinyl bag to help reduce reverb feedback. Take the tank out of the bag, turn it upside down and slip it back into the vinyl bag. Now the springs are hanging in the opposite direction. After you make the flip just re-install the tank back in the bottom of your amp mount the back panel and you’re done! This is a very easy procedure but just remember to be careful when handling the tank.