Singer 31-15 Industrial Sewing Machine Manual.
* Operating the machine.
* Needles and Thread.
* Removing and winding the bobbin.
* Threading the machine.
* Upper and lower thread tension settings.
* Oiling machine.
* Instructions for adjusters and mechanics.
* Time the needle with the shuttle.
* Adjust the transmitter starting lever.
* Parts diagrams.
22 page manual.