Hi, a lot will depend on your engineering skill ability as far as metalworking goes.......I would not advise touching the dovetails with anything except an oily cloth as they need to be fitted very closely but still free for CNC work.

If you assemble the dovetails dry and still get untoward movement as shown by an indicator against the table ends then perhaps a quick course in fitting is on the cards.

The very simplest move you could make would be to clean the dovetails and apply some mechanics blue to see where they touch or not touching, but that in itself is an art form and needs interpretation to be meaningful.

As this is a new thread the details of the machine are none existent......what mill is it, how old and how much work done etc etc.

If you bought it used then someone else might have attempted to "rework" the slideways and failing that just sold it on etc.

As I'm a fitter and turner (retired) machinery fitting is a trade I followed on and off for the last 60 years or so and you don't learn that overnight from a book.
Ian.