These are the older VAV's with the spline drive plug valves. Vintage "D".....1989.
I remember seeing those, but in that vintage i was dealing with spring rates and not stroke times...sorry. I don't think Trane was real big in to controls back then. They used a lot of Honeywell or JCI if my memory serves me correctly.
I know you don't need me to chime in on this, but it's 6 minutes.
Also, make sure you have the right RPM on the motor, I know there are at least two different versions; 300 RPM and 600 RPM. There may be more. I'm sure you can imagine what kinds of problems having the incorrect motor would cause.