I need to adjust the combustion blower trim on my TPI35. I've located the screw as per the manual but there is no indication at the screw or in the manual as to increments of trim affected by the screw; the screw simply turns in the socket. There also doesn't seem to be any thread on the screw so I can't rely on a tightening stop. Additionally I cannot detect a change in sound from the blower itself upon turning the screw either clockwise (increase) or counter clockwise (decrease). Picture shows the screw (blue component). Can anyone shed light on this?
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