Sounds like the problem is with the switch. First you might want to try exercising it. Quickly turn it on and off 30 or 40 times and see if this makes a difference. Sometimes switches get dirty or corroded and this may clean it up a bit. If that doesn't work, next I'd open up the cavity and see if anything looks out of place. I don't recall if the switch is sealed or not. If not, a little contact cleaner sprayed on it and then exercising again might do the trick. If it's sealed, or the contact cleaner doesn't work, I'd use a piece of wire to connect the leads (effectively removing the switch from the circuit) and see if the LEDs work properly. If they do, the problem is definitely with the switch and you may want to contact Alembic for a replacement.
Bill, tgo