With the first turn of the switch the capacitor doesn't actually connect. But it does if you turn it some more. So you have the option.

In an ac circuit a capacitor allows frequencies to pass but can greatly reduce others. So its main purpose was to reduce the mains humming at 60hz. (The tuner of an analog radio is basically a range of adjustable capacitors).

There were many badly designed and built amps and radios in the early days of sound engineering. It meant that they became live if the input polarity was changed. Easily done if you plugged in the mains the wrong way round. Added to that the venue might well have faulty wiring, causing reversed polarity and a poor earth. Typically an old church or such.

The so called death capacitor picked up a bad name because in some cases it failed and caused a short circuit in an already bad circuit (or one of reversed polarity) which lead to shocks and death. But it was never intended to be there as a safety device, its purpose was to reduce noise.

So the Gibbo amp may need a new capacitor to function as best as it was intended. For the purposes of authentic sound and that elusive feel. But probably best left to a professional to make that decision.

Older model amps can be converted to safer electrical connections. But this might mean changing quite a lot more in the power supply stage.

Using: Dell 3268 i3, 8 GB ram, windows 10. Biab version 2017 standard package, no extras.