Tab and carrier return cords installed at proper tension

DRUM ADJUSTED UNTIL THE TRANSPORT PULLEY POSITION WAS AT LINE

It took a few more iterations than I expected, in part because the drum would slip if I didn't really tighten the screws down quite firmly. It felt as if I was on the edge of material failure on the screw when I attained the final tightness that left the transport pulley at the target position .

Left edge of slider right on scribed line

THE TAB POSITION SLIDERS WERE GUMMED SOLIDLY IN PLACE

Tab positions are controlled by a long cylinder running from left to right behind the carrier rails, with a rotating slider for each of the columns across the page. Moving the slider in one direction allowed the carrier to sail past it unimpeded during a tab operation, while placing the slider in the other direction would trip a latch on the carrier to stop the movement at this column. 

Pushing the Tab Set or Tab Clear button on a typewriter (an up/down toggle switch on the 1053), causes the slider at the current column position to be moved to either the set or the clear position. As a convenience, when doing a carrier return, if the Tab Clear is held down then the carrier resets the sliders on all columns as it returns past them. 

These sliders were stuck in place by solidified lubricants, requiring me to flush them out with clock oil and work the sliders back and forth until they moved freely. With that done, the tab operation could work as intended, moving the carrier right to the next column that had its slider set. 

Tab sliders move to set or clear positions

ESCAPEMENT MECHANISM CHECKED FOR PROPER OPERATION

The rear of the carrier has a set of levers that are connected in a complex way. Two of them have pawls that engage in the teeth of their associated racks.  Another will force both of the pawls out during the carrier return and the tab movements. 

The space rack is what holds the carrier at its current column against the pressure of the mainspring and tab cord seeking to pull it rightward. The escapement lever can pivot its pawl out of the rack, the carrier begins moving, and then a spring pulls the pawl back into the next tooth of the rack. This moves the carrier a single column to the right. 

This lever is moved by a long bar running just behind the carrier, which pivots during the end of the a character print cycle to cause a one column advance. It is also pivoted by the operation of one of the two operation clutches, when the space button is pushed on the front of the 1053 or when the space solenoid is activated. The button or solenoid trips a clutch, rotating a cam one half rotation during which the cam moves levers that, in the case of a space function, pivots that bar that moves the escapement lever.

A second rack is offset a bit from the first and has pawls on the backspace lever that insert into the rack. If the backspace solenoid is activated, it trips the same clutch as was used for space, but the cam moves levers that engage the backspace pawl and drive the carrier back one column. The escapement pawl pops out of its rack and into the tooth one position behind. 

Finally, the escapement and backspace pawls are held out of the teeth of their racks during the long movement operations, tab or return. Another pivoting bar behind the carrier moves those levers out of the way. In the case of a tab operation, whose distance is determined only the the sliders that are in the set position, some levers and springs hold the pawls locked out of the teeth but when a set slider strikes a small projection on the carrier it releases the pawls to lock the carrier at that position. 

The escapement and backspace pawls plus tab latch levers