That machine looks to be in great shape. Nice score. One thing I have to do with mine is run dust collection to it to keep it from plugging up the chute. It doesn't take long forme to plug mine without using the DC and it is a bit of a pain to unplug it when it happens. The chips pack in pretty tight so it takes a little effort to get them out. Never use a belt sander to get rust off. It's hand work only. A power tool will take too much off to fast and too unevenly. I don't know if you will ever get rid of that ring from the glass. I have one on my TS from a kid that was in my shop with my son and he sat a cold beer down on it. Although there is no loose scale, the ring is clearly visible since 15 years ago. As long as it isn't rough to the touch it shouldn't affect the operation of the jointer. Lee Valley used to sell a product called Waxilit for making the tables more slick. I think it's still available but maybe not from LV. Whatever you use has to be silicone free.