The KA is of the K series of Monroe calculators produced from 1921 to 1928, with the A meaning Automatic, that is, with an electric motor attached.
Ever been at a garage/boot/stoop/yard sale,...
Monroe KA Teardown
These are some common tools used to work on this device. You might not need every tool for every procedure.
Probe and Pick Set
Precision Tweezers
Digital Caliper
Heat Gun
Mako Precision Bit Set