searching for motor brushes for antique Skill Saw
You caught me by default , you should also post this under tools, however I have rebuilt many electric motors so perhaps I can help. If you have the old brushes and there are removable springs or contacts ,one option may to manufacture a new matching brush from a similar sized block of a larger brush. I have never had a skill saw apart , but an armature has a specific curve when new and generally more of a worn curve as it ages, like an apple core rather than straight. If you can remove the armature and wrap firts course and later fine wet dry sand paper inside out around it, then file a larger carbon brush to near matching face conture, and insert into the brush holder. With gentle manual rotation you will be able to polish the new brush into the correct contour. This takes patience. Option 2 would be to find an old time repair shop who may have 44 year old parts, but the tools didn't wear out back then.....
Post a pic of the devivce and the brushes and perhaps a tape measure beside for dimensions if you can.