Microwave MW8781SB the timer no longer works, nor does it beep when i press it. i can set the clock, and cook stuff, but can no longer use the timer. i've unplugged it for 30 seconds, and reset the clock, and yet, the 6 preset times, plus the Power, Timer, and Cook buttons no longer work. the cook by weight, defrost and all the lower buttons and child proof lock still works. the cplock is not on btw, as i can still cook manually how can this be fixed ?