Without getting one of mine out, I seem to remember that one of the reasons that it doesn’t operate very well is because of the angle the reverse unit is mounted on the motor. Ideally it should be vertically mounted but it isn’t, memory tells me it is about 15-20 degrees off vertical. This hinders the armature from operating smoothly, especially when it wants to drop when the power is removed.
As an experiment lift the front of the engine about 20 degrees and see if it operates any better when you cycle it under power.