Johnny-cat

On the driver's side door, when I turn the key to lock and arm the alarm, the switch works only intermittently. I have to stand there and turn, and turn, and turn until it might work. When I try the switch in the unlock position, it works every time. All the doors unlock! I completly took the door apart to get to the problem, only to find the switch intact and all connections tight. My guess is that is worn out. Is there a replacement for this? Is this switch avail at the dealer?