Fixing A Fender Champ Amp | The Metal work

With the old circuit board removed, attention turned to the chassis. Vibro Champs have two extra controls for Speed and Intensity so you need to make two new holes in the front of the chassis, each side of the existing Treble control. To mark the position of the new holes the Champ faceplate has to be removed.
Simply unscrew the nuts from the jack sockets, control pots, switch and the bulb cover, and the faceplate lifts straight off. Stick some masking tape in the spaces each side of the Treble control and temporarily fix the new Vibro Champ faceplate in place by replacing the nuts. Everything should line up perfectly, and you can trace around the faceplate holes where the Treble and speed controls will be located.
Remove the faceplate and carefully drill two pilot holes in the exact centre of your markings. Then gradually increase the diameter of the holes using wider drill bits or, preferably, a cone cutter. Then simply reinstall the three original controls and fit the new 3M Speed and 25K Intensity controls. Early Vibro Champs had a small slider power switch rather than the toggle switch fitted to my amp, but fortunately Marsh amps supplied me with the correct switch and no metalwork was required to fit it.
Fender used the same chassis for the Champ and the Vibro Champ so there's plenty of space for that extra vibrato valve socket. I made a hole halfway between the existing 12AX7 and the 6V6 sockets using a Q-Max punch. They cost around £7, but if you plan to do more projects like this it's well worth the investment. I also drilled two small holes for the fixing screws.
The valve heaters are daisy chained and Fender had left enough length on the heater cable for me to cut it in half and connect the ends to pin 4 and 5 of the vibrato valve socket. Like the other valves, pin 9 was connected to ground then a 470K resistor was soldered between pins 6 and 1, with the tail connecting pins 1 and 7.