You never have told us what this motor is associated with and if there is a labeling that identifies its fractional horsepower , and / or /current consumption concerns or wattage.
As well, there is quite a large gauge of copper wire that goes over to, and is being spot welded to one connection of the overload protector.
Zeroing in on the circuit protector might be related to finding more cryptic numbering on other sides. With the shown visible manufacturers proprietary numbering being of minimal help.
I give your units 1 µF capacitor a 99.86% probability of still being good.
Using that capacitor as a measuring gauge, it looks like that might have upwards of 1/4 inch motor shaft .
This cluster of ancillary parts are associated with minimizing radio frequency interference when the brush contacts move between the segments of the rotor as it turns. A much higher voltage than your supply voltage is created at the instant of the opening of a connection between segments .
Those high voltage spikes need to be absorbed by these components.
Your found diode is being a bi-directional transient voltage absorber.
That arc suppression also cuts down on the electro - erosion of the segments of the rotor .
As things are currently , you need to initially examine the condition of the remaining brushes to see if they will be of adequate remaining length to press firmly into the rotor .
If I had to test further myself, I would either be placing a large solder blob across the circuit protector terminals, after I got them well tinned, or else use fine bare copper wire from an AC cord to tweezer wrap enough / many turns around to establish a good short across the two contacts , yet not short to anything nearby.
Next you mechanically reassemble the motor completely .
Then you hook up power to one lead of the motor and use the other power wire to RAPIDLY brush across the other motor terminal JUST long enough to ascertain which direction the motor is going to turn . Lock that into your neural cache memory.
Take a DVM . . Or analog meter . . . and set it up for DC current and 10 amps operation and insert its leads in series with one of the power wires.
Two people should be required to do this, but I have one person ready to make contact with the other wire from the power to the free open motor terminal just after the first person has grasped the motor shaft between thumb and fingers and given it one HARD spin in the earlier ascertained running direction, while applying the SAME voltage polarity to its terminals.
This minimizes hard start up current, which might exceed 10 amps.
Do a short analysis on the motor running, to evaluate for jerky operation due to bad winding segments.
Finding the correct circuit protector would be related to finding it from the manufacturer, or incorporating the current consumption now found to relate to.
Before there even WERE circuit protectors we would use a twice the normal run current, slow blow fuse externally.
As best as I can see ,there seems to be no mechanical to thermal coupling considerations inside the motor .
Thassssit
73's de Edd