If you are arriving at this entry for the first time, this is a comprehensive guide on how to re-wire the potted motors found on vintage Singer 15-91 and 201-2 sewing machines. It is my attempt to walk someone with zero experience through the entire process.
For your convenience, here are links to all 20 entries in the series. This way you can bookmark this page as a Table of Contents and quickly get to the entry you need.
Part A: Skills Building
1: Wire, Wire Stripping and Wire Braiding
Learn about the tools and wiring basics you’ll need to know to re-wire a motor.
2: Tools & Materials Required for Soldering
Learn what equipment you'll need to complete basic wire soldering.
3: Learning to Solder
Learn and practice basic wire soldering.
4: How to Terminate Your Wires
Learn how to create connections for attaching wiring to power terminals.
5: Covering Wire Joints with Heat Shrink Tubing
Learn how to clean up exposed wiring.
6: The Underwriter's Knot
Learn how to tie wiring into a strain-relieving knot.
Part B: Motor Disassembly
7: Disconnecting the Motor Leads
Learn to detach your sewing machine’s power terminal and wiring.
8: Motor Housing Removal
Learn to take the motor off of your machine.
9: Grease Wick Removal
Learn how to remove those grease wicks and where to get replacements.
10: Motor Brush Removal
Learn how to take those motor brushes out and look for signs of motor trouble.
11: Armature & Worm Removal
Learn to remove two crucial parts of your motor.
12: Detaching the Field Core
Learn how to safely crack the motor open.
Part C: Making Repairs
13: Cutting and Prepping the Motor Leads
Learn where to cut the bad wiring off.
14: Replacing the Motor Housing Grommet
Learn how to remove a cracked rubber grommet, where to get a new one, and how to put it in.
15: Soldering On New Motor Leads
Learn where and how to solder on the new wiring.
17 (Yes, this is out of sequence): Cleaning the Commutator
Learn how to clean off a crucial element of your motor.
Part D: Motor Re-assembly
16: Re-attaching the Field Core
Here we start putting the motor back together.
18 (Yes, this is out of sequence): Re-installing the Armature and Worm
Learn the tricks behind putting these two crucial parts of your motor back together.
19: Re-installing the Brushes and Grease Wicks
Learn to easily re-install these correctly.
20: Hooking It All Back Up
Here in the final step we finish up the wiring, run the motor in, and put it all back together.
[A caveat: I hope you'll be able to bring your potted motor back to life with new, safe wiring, as shown here. But please be aware that these steps are not an absolute guarantee of success, as a small percentage of motors may be completely burned out, which is currently beyond my capabilities.]