I bought this adapter for my chumby one and it just doesn't work. The connector does barely fit, but my chumby doesn't power on. I bought a replacement chumby one from ebay, and the original power supply adapter that came with that works just fine, so the problem is with the adapter and not with my chumby.
I also bought an AXIS AC Adaptor on ebay for AXIS IP Cameras (referenced by another poster on these boards) and that supply didn't work either! There are a number of listings for the Axis adapters, so maybe I bought the wrong one. In any case, finding a replacement power supply for the chumby one is definitely a pain in the rear.