Cause of escapement drum 'skipping' discovered and corrected, back to setting up cord tension

SKIPPING CAUSED BY PARTIALLY ENGAGED CARRIER RETURN SPRING

The sporadic grabbing or skipping that I was experiencing is due to the carrier return 'shoe' still partially engaged pressing on the spring to drive the escapement drum in the carrier return direction. The shoe should be away from the spring to allow the spring to rotate freely around the operational shaft. When the shoe presses on the spring, it winds up so that it is clutching on the shaft and causing the spring to turn with the main motor (operational shaft). 

The C.R. Clutch Arbor in the diagram above is turning with the operational shaft, but the C. R. Pinion is not directly connected to the C. R. Clutch Arbor. Instead, the coiled C. R. Clutch Spring turns over the Pinion but does not have enough grab or force to turn it. 

When the Nylon Shoe is pressed against the far end of the C. R. Clutch Spring, however, the spring is quickly wound tight by the C. R. Clutch Arbor, thus gripping around the C. R. Clutch Pinion so that it turns with the operational shaft. This pinion turns the drums and shortens the return cord to pull the carrier back to the left side of the machine. 

The Carrier Return Clutch Arm in the picture above is what moves the Nylon Shoe so that it either presses against the C. R. Clutch Spring or is not in contact with the spring. The adjustments on the Carrier Return Latch are what determine the grabbing force when engaged and the position away from the spring when not engaged.

ADJUSTING THE SETTINGS SO DRUMS TURN FREELY WHEN NOT IN CR MODE

Nylon Shoe contacting spring

Activating rod to Nylon Shoe

At the rear of the typewriter are these two adjustments for setting the action of the shoe to engage or release the carrier return clutch, implemented as a spring over the operational shaft. I loosened the lower adjustment and allowed the mechanism to move the shoe further from the coil spring when the return is not engaged. This eliminated the sporadic grabbing or skipping, which was the problem affecting my cord tension setting over the last week or two. 

Adjustments for CR clutch engagement