If no one responds there is a least one thread that explores alternative methods. The Factory Glow Plug Reamer has an OD of 7mm.

A 7mm Drill bit with the Flutes greased and turned carefully by hand would work
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I also think a Bronze Gun Cleaning Brush would work; but when I suggested it one of the members worried a bristle on the Brush might break off. I believe if you packed the brush with Grease that is unlikely to happen.

If you are handy with tools some have made a Reamer with by using an old Glow Plug; drilling it out to fit a Drill Bit and welding the drill bit on the Hex End. I do not see how the drilled the hole down the center witho out a Lathe; I guess I am not a skilled as some.

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