Those tables now look tremendously better!
I believe that the “deep scratches” are actually machining marks from the original factory flattening process, known as “Blanchard grinding”. The brief video below shows the process and resulting finish.
On machine wear surfaces, having machining marks visible is usually considered a good thing, as a lack of them may indicate excessive wear.
It’s dangerous to use a jointer for a too-short workpiece. I forget the recommended minimum length for a Shopsmith, but it’s on the order of a foot, and is equal to the distance between the two bumps atop the jointer fence. As long as a workpiece of that minimum length easily bridges any low spots, they shouldn’t affect accuracy.
The small rust pits are strictly a cosmetic issue, except that rust likes to re-form in them. To prevent that once and for all, apply Penetrol generously to the entire surface, rubbing it well into the pits, and then wipe off the excess. Let it dry for a day or three. Then clean the Penetrol off of the top surface with mineral spirits, but not so aggressively as to clean it out of the pits. Finally top-coat with JPW (Johnson’s Original Paste Wax) or equivalent, and it’s good to go.
If you have any more machined surfaces to de-rust, I highly recommend
Nyalox brushes. Chuck one into a power drill — or onto your Shopsmith spindle for small parts — and they make quick & easy work of de-rusting. The medium and fine grits knock off surface rust while removing almost no solid metal, and they’re much nicer to use than an old-fashioned wire wheel. They also work great for polishing metal after treating it with Evaporust.
