Update:
First, a thanks to the mechanics and parts guys at Wallace Tractor for advice and a replacement bolt. I had a little trouble getting the replacement bolt started but at their suggestion cleaning it up a bit with a 14mm die solved that problem nicely. Thanks guys.
Second, as the Wallace team pointed out, the loose/missing bolt was not a motor mount but rather the loader support bracket attach point to the motor.
Third, on review of the KL401 owners manual there are clear instructions to retorque those bolts every 25 hours. Oops. I wonder how many of us are doing that. Until now I certainly hadn't even looked at the manual in oh maybe 225hrs or to be precise on the delivery day that Rick drove it off his trailer.
Fourth, the manual lists the appropriate torque specs. However it is a real btch to get 120 ft pounds of torque while on your knees and reaching under the tractor with one arm.
Fifth, use red locktite
Sixth, I promise to retorque these and other bolts at least every time I change the oil and I'll try to remember every 25hrs.