My electric toothbrush used to have two speeds, press once for slow, twice for fast, a third time for off.
Now it goes from off to fast to off.
It's not likely to be switch bounce, as it's totally consistent. I assume it has a micro, as it does the little glitchy thing to tell you when to move to another area, and when to stop.
I'm not going to try and fix it or anything, but it seems a bit unlikely to me that some memory location had failed with this precise effect. If it was made by Apple, I'd say they'd reprogrammed it to encourage me to buy a replacement.