Hi, there seems to be a problem with my Nano Small Stone. I bought it about a year ago, and it has not exhibited this problem in a while; however, it does this regularly.

Sometimes when I turn the Rate knob to its maximum value, I hear a relatively loud buzzing noise and there is almost no phaser effect to be heard. On some occasions, this persists even if I turn the Rate knob to another position!
When it starts acting up like this, I can usually remedy the situation by unplugging the adapter and plugging it back in.

What is wrong with my Nano Small Stone?

Thanks,
oscillator