It looks like the the machine was ground or it was scraped and it is wore off and then 1/2 mooned flaked. Flaking when new was .002" deep and the scraping was a min of .0002" to .0005 deep. I don't see any scraping marks, and the 1/2 moon flake is all that is left, so it is worn .0015, so you will have to live with it unless you have a pro re-scrape the ways. You may have run a machine with rollers and you expect your machine to feel the same. You may want to buy a set of these. https://www.dunbarrollers.com/products.php?manufacturer=14
You might try running a lighter oil. Once machines wear like this, there tends to develop a lot of viscous drag or oil shear when using standard 68 weight way oil with all its tactifiers. I have run similar machines with high ratio cable drives and plain bearing ways and had good results with 32W hydraulic oil. If you place your most sensitive indicator against the chuck and traverse the table quickly for a few passes, you may see that the thicker 68W oil develops an undesirable amount of lift with the worn ways. These machines were designed to float on a very thin film, a couple tenths at most. I agree that your ways are worn but this might get you by.
Here in the Detroit area, one might go to Production Tool(PTS), or to Expert Machine Sale on Grosbeck Highway to try a new or rebuilt manual scraped ways surface grinder in order to determine if the Ops grinder is sluggish..
*Perhaps the Op could find similar places in his location.
Carbide Bob may have a similar machine, so might offer an opinion of how much hand pressure is needed for long travel. Perhaps in pounds of pressure or how many fingers are needed to push the long travel hand wheel.
OT: If I was a surface grinder instructor I would tell grinder newbies that if you can push or disrupt a surface grinder set-up with a 3-finger push it is not a safe set-up and so needs much caution or revising the set-up.
Likely I would draw various parts and then draw in the set-up assistance needed to make the part secure.