Thanks Paul and Pete
Pete, you're right. I couldn't find a catch, or spring release but... The spring holds the yoke of the arm at an angle to the spline of the motor. Which, if you can't release this tension, creates the new volcabulary and need for Bactine. $7.00 is the easy way out.
Another tip. I used a heat shrink hot gun to heat the arm mount to about 900 deg F. That really helped to break the rusting weld it had formed.
'c'