A rotary switch is a switch operated by rotation. These are often chosen when more than 2 positions are needed, such as a three-speed fan or a CB radiowith multiple frequencies of reception or "channels".

By changeover switch, if you mean forward reverse switch, the correct electrical terminology you should be searching is, wiring of an electrical drum switch.

Rotary switches can be researched by visiting your local DIY store or searching the internet. They are switched that are operated by rotation. A common example of a rotary switch is a channel selector on an old fashioned radio.

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It comes out with a screwdriver - it is held in place with plastic clips.