Old Fan Runs Very Slow And Hums
Improper replacement filter or phase-shift capacitors can e.g. burn out brushes or lead to greatly increased thermal losses in windings, which can burn isolation and lead to fiery failure.

If possible I would like to repair the motor and not completely replace it as its an antique fan and I would like to keep the parts as stock as possible.

How antique is &quot;antique&quot;?
Because, honestly, I don't trust old consumer-grade motors. It might be wise to replace the motor to preserve the rest.
The things you can service about the motor are bearings, and if it is brushed, you can replace the brushes.
Everything else will come down to removing the windings (which is prone to exposing you to dust of enamel that might contain unhealthy fire retardants) and winding it yourself, which is neither going to be good as new nor easy or quick.