The wonder of these machines to me is that, like a classic piece of literature, you learn something new every time you come back to them. Calibrating the thread tension unit led me to diagnose and treat a very interesting problem that I haven't found mentioned elsewhere; I explore it here in case anyone else has a similar difficulty. Then I finally get to calibrate the unit , which was my original intent all along.

I had lots of help getting to this point, and I hope my video adds to the knowledge that's out there! Here are some excellent references for a lot more background in case you want to know the basics of disassembly and reassembly, and for some of the influences that contributed to my opinions about calibration.

Archaic Arcane on rebuilding a 500 series tension unit:
   • Singer Rocketeer (500/503) style On m...  

AndyTube video that includes “zeroing out” and other considerations for the thread tension unit:
   • How to Remove, Clean, Replace and Adj...  

AndyTube on how to make a new Tension Pin:
   • Repair and Reinstall the Tension Unit...  





Music credit: TeknoAXE: Bubble GFunk sans melody