Ah thanks Klause, but what about that small drilling at the lower end of the block that aligns the block with the main carb housing and consequently aligns the slide, using the small external screw, if the jet block is rotated 180 degrees, this small drilling will be not be correctly aligned because that small screw that normally keeps the block aligned, would now 'float' within that larger 'choke' drilling. So the jet block (and slide) could be maybe 10 or15 degrees out of line.
?