I got a reply from Ivy about PAS problem. She suggested that the throttle being to close to the control buttons could cause electrical interference so I move it about an inch away and that had no effect. I disconnected the brake sensors one at a time and then both and no effect. I made sure all connectors are dry and fully connected, no effect.
I've discovered that the only way to get the PAS working is a quick push on the throttle. Sometimes by reverse pedaling quickly it will come back on line but this is not an option when climbing a hill. As long as I don't come to complete stop most of the time it will continue to provide assistance. If I slow down to much and stop pedaling it cuts out and a jab of throttle is necessary to get it on line again
It seems like it's a problem with the torque sensor. Prior to this problem the PAS would initiate by barely moving the pedal, which sometimes was a little dicey when I am picking my way through a narrow space and needing a little forward motion, the bike would lurch forward. I would keep one hand on the brake to cut the power.
Has anyone had the motor apart to understand how the torque sensor works. Could the contacts be contaminated or could this be a faulty sensor and how hard is it to replace.
I am writing this update of the above post which was based on all the things I did yesterday afternoon.
Today I took the bike out again for a 16 mi ride and it worked like it had before the problems mentioned above. I didn't do anything other than reset the trip mileage before I took off. What ever caused the problem will remain a mystery and I hope it doesn't happen again
Thanks to the folks who offered suggestions for a fix