On the Rung Fo bases I have seen and helped re-scrape the 4 pads that sit on the top of cabinet are way off. One I believe was .011" high when we set it on a granite surface plate. So if the cabinet is flat and when you tighten the hold down bolts the base twisted. I get a bit anal sometime when it goes to accuracy. The machine is not a Bridgeport or Moore, so maybe it's OK as far as accuracy goes.
By chance do you have a surface plate? If not, don't worry about it. I just again looked at the pictures and when you set the base on the cabinet shim under the 4 corners so they all hit on what ever cabinet you set it on. so when you tighten the 4 bolts it doesn't twist.
I could get into precision ways to improve this by using 3 points, etc, etc. Sometimes hard to help of teach if you don't have the equipment to do so. So just give it a try and if it works good, use it. Rich