With the jointer turned off, set the table height relative to the blades. Once satisfied, turn the jointer on and run a 2' board through, stopping th e board just as the board clears the blades. Push the board back to the t urning blades and if you detect a significant contact, then raise the table just a tad. Run the board through, again, stopping just past the blades a nd reverse the board again until it touches the blades. With the jointer running, you want the board to just barely touch the blades when pushing th e board back into the blades. This accommodates a blade that might be a t ad higher than the others.
Jeff explained, with the jointer at rest, the very slight play in the beari ngs may make a difference in table height relative to the blades, as compar ed to when the jointer is running. When the jointer is running, that possi ble play in the bearings zeros out any play, when the turning head centers itself within the bearings.
Setting the height, when the jointer is at rest, may not be as perfect as i s needed, whether using a gauge or a metal rule/bar. The true test is with the jointer running and using the wood you're working with, especially if you don't have a precision gauge or a metal straight edge (jointer turned o ff).
I hope I explained this well enough.
I need to change the blades on my 8" jointer, so I'll check out this techni que. Certainly sounds reasonable and I'm certainly confident that Jeff kno ws what he's talking about.