EV 100 clutch disengages itself

[garybuyit]

Last time out on the boat, the autopilot clutch lever "de-clutched" itself many times during a 4 hour sail. The lever simply moved up, away from the gears. Most times it didn't completely disengage from the gears, and we held course. However, if I didn't notice it right away, it would fully disengage, and the boat started wandering off course. It did this every few minutes. Has never happened in the past. Under sail, not power, downwind, 15 -- 18 kts. of wind. Coming home two days later, it happened a couple dozen times during the 4 hr. sail. Again, under sail downwind, with 12 -- 14 knot winds.

This is a new autopilot, installed February 2015, has worked flawlessly until 2 weeks ago when the problem occurred. The boat is a Nonsuch 33, 15,350 lb. displacement.
Nothing appears to be loose on the autopilot ring containing the gears, or the clutch lever itself. When I engage the clutch, it goes firmly into place. Where do I start troubleshooting?
Thanks,
Garybuyit