The adjustment is really only critical on the right side, the left side is two positions and hard against the end both ways.
The trick is finding the spot in the middle that engages the direct (third) gear. Mark that spot on the shifter, and you know where third gear lives. First and second are cable fully taut, fourth and fifth cable slack.
Both cables slack is fourth gear.
Back to my previous post where I said the hub failed. The owner reported that his son claimed it was not working. Not long after I posted this, the bike came back to me and I was able to determine the hub was fine. Too much exposure to the elements had seized the cables. I installed two brand new ratcheting friction shifters, and all was well. Works like a champ.