This restoration is on a 1920s armature tester or "growler" made by the the Armature Rewinding Co. I believe this is the patent: https://patents.google.com/patent/US1... 0:00 Intro 0:30 I do the thing 16:54 How a growler or armature tester works Even though this is a simple tool with no moving parts, it proved to be quite a challenge as I have never rewound any electrical components for my restorations, until now. It was really fun to learn what needs to be done to rewind a simple transformer and exciting to see if you did everything correctly or if you perish from electrocution. I am having a very hard time finding information on this specific tool as my research has only lead to a few mentions of the company and some advertisements, but nothing on this exact tool ever existing.