NO on the WD-40 (Stands for Water Displacement formula #40) when it dries it leaves a residue that is not a lubricant and will actually stick the machine up.
Use Tri-Flo or sewing machine oil. Really. it will loosen over time. Sewing machine oil also leaves a residue (varnish) but it is not as bad as the WD-40. Tri-Flow is a silicon based product that leaves a silicon residue which is still a lubricant even when dry.
A more expensive solution is Kroil. It is a penetrating oil that is very popular with gunsmiths and the like. but it is 2x the price of the others.
Using the heat from a hairdryer will also help (be careful metal parts heat up quick)
I am currently working out a method to reliably make replacement slides for folks. I make the straight ones no problem, but the ones with the "bite" taken out are more challenging to get correct on a reliable basis. I even have a sample that I am working from to copy.