hardware problems with s4

Hi guys dont know if im just unlucky but i am on my second s4 the current one was replaced last november and now i am having trouble with the channel 1 & 2 cue buttons being unresponsive same is now starting with my deck 2 play button, I work between 4 and 5 night a week so the unit is well used, my original s4 had hard buttons the replacement I got last year had these rubbery buttons, i suspect the bottom of the rubber is wearing out and so no longer makes good contact with the micro swith beneath, I have contacted NI still waiting a response, does anyone else know of this as a known issue? seems to be a bit of a design flaw!