Hard to say without looking at it, but the bearing would be my first 'guess' since it is a primary part for rotation. Bearings are available so it could be worth a try.
I hope that you will have the full restoration video series of the PA motors in 300-700 series Singers. At that time you will probably explain that the Oilite or oil embedded sintered bronze bushing at the commutator end is impregnated with SAE 30 oil during its manufacture. I am a big fan of these sintered bronze bushings. Although they are sometimes listed as oil-less that is further from the truth. The microscopic holes in the sintered bronze bushing are impregnated under pressure with the SAE 30 oil. Except for the earliest Singer 301 sewing machines, the service manual for the 300 -700 series Singers probably does not recommend any lubrication. They did not plan for these sewing machines to still be in service this long. Of course, you are a proponent of longer service life for these vintage sewing machines. So I concur with you that some form of lubrication is needed to continue the life span of these machines. Honestly, I never understood why Singer recommended grease lubricant be placed in the wicks for sintered bushings. I thought it should be SAE 30 oil like you are recommending. Thank you for posting this video. I am looking forward to the more extensive 301 motor maintenance video.
That's the truth I have a 301a that came from a high school that is like new, zigzag attachment everything then I have my mom's 348 robin egg blue that is a workhorse with all steel gears and 13 more. They're all workhorses even the old black ones
Do you have any comments about the PA motor with the grease tube? I have one, and according to the manual, I am supposed to fill the tube with grease. However, there is the wick in the tube, and practically no grease goes into the tube! Thank you.
Hello. I have never come across one of those myself. It is heavier duty than a home machine, but would be considered a "Light Industrial" or Commercial Tailor's machine.
