Replacing the pilot mixing tube was one of the more difficult tasks to accomplish in the restoration of the pilot.  The old tube had to be drilled out without increasing the casting hole that the tube had been press-fitted into.  This required highly accurate mounting of the casting on a milling machine and then carefully milling out the old tube.  With this accomplished a drawing could be made for the replacement pilot mixing tube.  Once fabricated (this time of stainless steel) the tube was pressed back into the pilot casting.