It may have been a design change to increase the coverage of the way oil. I suspect the cross-slide never never travels past that section of the bed so it isn't exposed to the air. I also suspect the operator side of bottom of the cross-slide has oil groves in it and they never get exposed to the air. Yes those 3/32 Bijur pipes either plugged up or got smashed. I prefer Zig Zag oil groves as they spread the oil over the entire flat way. In the old days they used straight groove that were a disaster because the mating surface didn't wear and made a raised area and once the surface were lapped together the ways never got oil outside the groove and scored up. That was a nice feather (kidding)...straight oil grooves made the machines wear faster and they needed to hire me to fix it.....lol