My HS220 doesn't consistently follow when I push its button.

When off, pushing the button won't reliably turn it on.  Sometimes it takes a number of pushes.

When on, pushing the button won't neccesarily turn it off.

   Sometimes I push it a second time a few seconds later, and then it turns off, and back on immediately.

   As if the first press was queued up, and eventually the device performs all of the 'saved' operations.

Does anyone have any ideas?

(I only have one of these switches, so I have nothing else to compare it to.)