Been in touch with Jeff at Northfield and he told me how to set the height of the jointer outfeed table.

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 the board just as the board clears the blades. Push the board back to the turning 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 and 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 the board back into the blades. This accommodates a blade that might be a tad higher than the others.

Jeff explained, with the jointer at rest, the very slight play in the bearings may make a difference in table height relative to the blades, as compared to when the jointer is running. When the jointer is running, that possible 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 is 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 off).

I hope I explained this well enough.

I need to change the blades on my 8" jointer, so I'll check out this technique. Certainly sounds reasonable and I'm certainly confident that Jeff knows what he's talking about.

Sonny