In this video, see a vintage 1945 U.S. Army Signal Corps EE-8 field phone disassembled and given some basic maintenance. Maintenance includes lubrication of the hand crank generator and polishing of contacts for the microphone element (transmitter) and the earpiece element (receiver).

This field phone and its variants saw service for over 40 years through WW2, Korea, and Vietnam. Using phone-to-phone wired connections, it could communicate up to 17 miles on two D batteries. For more information, look up technical manual TM-11-333.