We have no way of testing this machine, so please assume it is not working / for display.  

From John Wolff's Web Museum:

Monroe Model KA-161, S/N 123970

Technology: Stepped drum, AC motor drive

Digits: 8 keyboard, 8 counter, 16 accumulator

Dimensions: 12"W x 15"D x 8"H, carriage width 16", overall 19"

Weight: 43 pounds (19.6kg)

Manufactured: Orange, New Jersey, 1920s

Model KA from 1922 was the first Monroe calculator with an electric motor drive. The machine has an AC induction motor of about 5" diameter mounted externally on a cast-iron bracket at the left-hand rear. The motor occupies the dead area under the extended carriage, and so requires no additional desk space. The motor rotates in one direction only at 1500RPM. The mechanism is driven through a planetary gearset, with two dog clutches operated by the Add and Subtract bars to select forward or reverse rotation. The case has been widened by an inch and a half to accommodate the control mechanisms on the left-hand side. The winding handle has been replaced with a knurled brass knob, but the crank can easily be re-fitted to operate the machine by hand.

The carriage has glass windows above the numerals, but carriage shift and register clearing are still manual. The item count knob is at the lower left of the keyboard, with an additional control lever at the upper left to silence the bell.

This machine has separate aluminium cover panels with linoleum linings, and is finished in a high-gloss black enamel. The motor nameplate gives the address of Monroe's head office, which was in New York City until the mid-1920s.