There seems to be a tension spring. The pedal goes down 1" and hits more resistance and goes down another 1" or so and stops. It stays there, but can be returned with little up pressure to center it. I don't have a manual, so I can't see where a tension spring goes.
I found the problem. The arm that holds the roller is mounted to the frame like a banjo bolt. The mounting is worn out and the arm moves away from centering v block as the pedal is moved in the forward position. The roller slips off the v Block and slides up the side of the v block where it binds the mechanism so it won't return. I attached a piece of strap metal bent with an offset to the frame on an existing frame bolt extending upwards so the arm slides against it instead of running off the track of the v block. If I have to rebuild the engine this winter I will fix the arm. This shouldn't have happened with only 600 hours on the machine. I have removed the spring I had attached earlier.
Thanks for all the help. You homed me into the correct area of the trouble.
I am very happy with this diagnosis. Tom