A light grease, don't use too much, it will just make a mess in the area if you do .
You've got a 40 year old starter, most likely all the lubrication in the starter is gone .
Don't know your capabilities, but if you can get oil at each end of the starter shaft bearings, they are a sintered type, granulated brass material that is pressed into a bearing, some engine oil or similar oil will help out .
Oil will be absorbed into the bearing material .