My son is looking at a Delta X5 DJ20 with a listed price of $1300 with a mobile base. Straight knives. Appears to be in generally good condition but can see rust on outboard end of both tables. I can’t tell for sure but it looks like the rust is deeper (at least on one end) than just superficial that can be rubbed out. If he can go after it with oil/Boeshield and ROS and even if some pitting remains, is there any reason to be concerned about the rust or the purchase?