The guys are right, simply call me and I will send you a new power switch.
Unless - - - your 240 is built in an old Dyna St-150 chassis using their original power switch. If that is the case we will need to see the amplifier to fix it. It requires taking the switch apart and de-burring the contacts as there are no new replacement power switches to fit that special application.
The power switches in all new AVA chassis units have internal red power lamps. The Dyna switch was not lighted, the on indication was on the other side of the faceplate, done with some small T53 light bulbs.
Let me know which version you have.
Regards,
Frank Van Alstine