Realistically you bought a camera made a long time ago, with unknown service history. Besides, when they assembled it, they did not take the utmost care, and the lubricants they used at the time were not ever-lasting either. There are technicians who can completely disassemble cameras like this, clean everything, and put it back together the way it's designer intended. Some who had their cameras rebuilt like that reported that they were totally transformed, but I do not have first-hand experiences. Certainly I used vintage CRF cameras but finally had to give up on them, as they're far from being spectacle-friendly.