I have older VTL monos and had the same problem. The switch on mine is a rocker. It is a generic switch that my tech ordered from a parts supplier. Works fine, now. Instead of getting it from VTL, a competent tech will take care of it. If you're doing it yourself, try some online sources, such as Parts Express.
I have the amps on a dedicated circuit, so, instead of using the new switches, I leave them in the "on" position and turn the amps on from the circuit breaker in my electrical panel.
I have the amps on a dedicated circuit, so, instead of using the new switches, I leave them in the "on" position and turn the amps on from the circuit breaker in my electrical panel.