First take off the top of the box. It is not sand but cast iron fine from the machining operation that is left behind and it will be in the pockets and hidden. It will be stuck in place lightly and to prove you have any probe the bottom of the box with a magnetic pick up tool. If you get any at all then it is advised to drop the quil out of head and thoroughly clean it internally. then with box open and on floor, power wash it thoroughly too. then re grease your top bearings and filter the oil and put it back together. After you are sure it is clean then you are ready to run it. I tried the short cut and did not get enough of the iron out of it and it was destructive to the system.
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