Switch it on and turn it up! Replacement toggle switches are available for most Fender® amplifiers.

DPST (dual pole/single throw) design toggle switch used as an ON/OFF switch.
3A, 250VAC; 6A, 125VAC. Threaded nickel-plated brass mounting bushing measures .462" diameter. Four solder lugs. Includes mounting nut and washer.

Used on '59 Bassman®, '65 Twin®, Vibroverb, '65 Deluxe Reverb®, Pro Tube Series, Blues Deluxe™/DeVille™, '63 Fender® Tube Reverb, Dual Professional, '94 Twin, Vibrasonic, Prosonic™, '65 Super Reverb®, Showman, Bassman® 300, '57 Twin™, Super-Sonic™ Series, Pro Junior™, Blues Junior™, Hot Rod Deluxe™/DeVille™, Princeton® Recording Amp, Bassman® TV Series, Super Bassman®, Bassman® 100T, '57 Champ, '65 Princeton Reverb®, EC Twinolux™/Tremolux™, EC Vibro-Champ™, Machete™, and '57 Bandmaster™ amplifiers manufactured from 1989-Present.