Actually, calling this a rebuild is stretching it a bit. However, this is what I actually did :

• Removed old wiring
• Restored old wiring posts
• Installed new grounded wire and plug
• 3D printed a new connector cover
• Re-assembled and re-painted the motor

The photos below show the motor after restoration, and the "before" as it was purchased (at an estate sale).

The nameplate on the motor was a bit beat up, but as near as I can tell :

• Model number : 410653
• Serial number : 5028685

Here is how the wiring is supposed to look (more or less) based on some photos found online :

As the photos show, the motor wiring comes out of the bell end onto two terminals (which are insulated by fiber washers from the end bell). The electrical power wiring then connects to the same two terminals, and the whole assembly is covered with a (presumably metal) housing.

Here is what one terminal assembly looks like when dis-assembled :

By removing the the four screws on the end bell I was able to remove the bell. The bell was slightly rusted in place, but by the use of some penetrating oil and some careful tapping with a hammer and wood block I was able to work it loose and remove the terminals :

After cleaning and masking I spray painted the end bell with Rustoleum gloss black 2x Ultra Cover. I re-installed the terminals using new 10-32 screws and new plastic (UHMW) washers (for the top washers only, which were cracked). I also drill and tapped (8-32) to add a grounding terminal. Note the two power terminals have top nuts of brass and steel to correspond the the Line and Neutral wires. The top nuts were missing on the motor when I got it; some pictures show the motor with knurled thumb nuts but I do not know if those are original to the motor.

With the terminals re-installed, the old power cord wires (which were soldered on and insulated with electrical tape) were removed, and connector wires were installed using butt splice crimp connectors and crimp on ring connectors. Note the green screw added for the ground wire.

With the re-wiring completed and the end bell re-installed, it was time to mask and paint the rest of the motor (and the two oil reservoirs, which I removed for painting. A note about re-installing the end bell: the four screws need to be tightened gradually in rotation (like installing a car tire) in order to make sure the end bell goes on straight. If the end bell is straight, the motor shaft should rotate freely by hand. Initially, all four screws are tightened with the terminal cover removed (to avoid cracking the 3D printed plastic cover).

With the rebuilt terminals installed, the wiring repaired, and the end bell re-installed, it was time to mask and paint the rest of the motor. I did not attempt to remove all of the old paint, but I did "scrub" the motor with a scotch-brite pad to remove rust and loose paint, and then wiped it down with minerals spirits to remove dust, etc.

I allowed the paint to dry overnight, and then removed all of the masking. Unfortunately the masking tape pulled up some of the paint (I should I have a wire brush in the cleaning), but this was repaired with some touch-up spray painting. The oil reservoirs (which I also painted) were filled 3/4 full with 3-in-1 motor oil (SAE20), and then installed on the motor along with their spring mounted wicks, after which I added additional oil via the oilers. These oil reservoirs, by the way, contained almost no oil when I removed them; fortunately they were not completely dry so I don't think the motor was ever run without some lubrication.

Here's the (almost) final motor after painting and re-installing the oil reservoirs. Still need to add the power cord and terminal cover :

The final step is to install the new power cord and terminal cover. The power cord is the easy part - I just happened to have a good power card in my parts supply. The terminal cover is a bit trickier - the original is long gone and I have no dimensions for the original. However, based on the pictures I found online of the same model motor, I was able to create a look-alike copy in 3D CAD for use in 3D printing (see below).

3D printing is a very good approach to making this part, and even has one advantage over the original in that the plastic part is insulating. I would guess that the original art was stamped out of thin steel sheet and then painted. The options for proving a replacement cover are these :

• Find an original replacement - unlikely to say the least!
• Make a cover out of sheet metal - possible, but with my sheet metal skills the result would be serviceable but not pretty
• Make a cover by milling out of solid stock - this could be done by manual milling or of course CNC milling (which I don't have). Manual milling would be a lot of work for uncertain results.
• 3D printing - since I have a 3D printer and what I consider to be a reasonably good CAD "copy" of the original, this is the obvious choice for me

I tried to make the new cover look as much like the original as possible although I did add some modifications to increase the strength. If you look closely at the photos below, you will see that I added extra reinforcement around the "ears" that connect the cover to the motor. My guess is that this is where the plastic part is most likely to fail under stress, so I thought some additional material at this location was a good idea. In addition I widened the interior of the base by adding a fillet to the bottom.

As a first step in making the part, I took some measurements of the location where the part needed to go, as well as some photos. By uploading the photo to CAD and "tracing it", along with the measurements I took, I made a first draft of the shape I needed. I then printed out a "skeleton" of the required shape which I then compared to the motor. The first and second attempts needed some minor adjustments, but the by the third trial I had a very good fit. This method of test fitting is very useful, and saves on both print material and time. Note also that I printed the test pieces in PLA as this is typically the cheapest and easiest material to use. However, the final part will be printed in black PETG (stronger and more heat resistant).

With the final version of the terminal cover ready, all that remained was to connect the power cable and install the cover. The photo below shows the connected power cable (with the terminal cover slipped onto the cable first, of course). Note the nylon tie on the end of the power cable to act as a strain relief.

The terminal cover had a good solid feel and was a perfect fit. I ran the motor for about five minutes to see if the bearings were heating up, but I could detect no signs of a problem.