a little late but, i had same problem on my S185. first some of the upper number buttons wouldn't work when cold soi had to change security code to use lower numbers. then periodically the start and stop buttons wouldn't work. finally after about 4 months of maybe starting, it wouldn't start at all. took out the control panel, took it in to bobcat dealer and they confirmed, it was the keyboard/control panel. bad news is that a replacement is over $800. i could go keyed but that's $200 or so.
feeling it's a waste to throw it out for a simple malfunction, i looked into it further, esp since i only had 500 hours on it. well, behind each button is a micro switch of course. after carefully pealing up/seperating the two membranes and exposing i could see where a silver contact was "in need of attention". carefully cleaned the contacts of the start and stop buttons, resealed everything and low and behold, it all worked like new.
if someone else is having "button" problems i can clean up and fix for around $80.
