The method I now use is much simpler and requires just an aluminium rule and piece of paper. The thickness of the paper represents how much the knives should project above the rear table.
Put the paper on the table, lay the rule over the block, bring the cutter out until it just touches the rule, then repeat at both ends of the block to get the knife in straight.
If at any time you wind the knife out too far, do not just wind the adjuster back in as there will still be some backlash in the thread. Instead wind it well in and then set the height as you wind out again. That way the knife will be seated properly on the adjuster. Always adjust by winding out.
Check and recheck either end then tighten the locking screws starting with the middle ones and working out to the edges. Repeat the whole process for the other knife, remove the paper and make a trial cut. If it scoops they are too high, if it tapers they are too low.