On Sunday, May 31, 2015 at 7:12:52 PM UTC-7, Bill T wrote:
Hate to launch again as an "experiment " without knowing what is really going on.

I'd suggest anchoring the glider, and using a come-along to tension a rope on the hook to some modest value, say ~150 lbs, and actuate the release. That will at least give you an idea of the relationship between tow rope force and actuation force. It will also show you if anything is distorting under tow force.