If you have an air compressor...
Use the compressor to blow out all that dust on the motor and It will look like new....just do it outside because it sends clouds of dust out but you will be so impressed with the results after cleaning it with the compressor...hopefully you have the compressed air blowing attachment, if not, they are cheap to buy. Most compressors come with them though.
I did this this summer on my model F from the late 50’s...wow what a difference, even the wires now look like new!
Jon
