The ribbon wrinkles. Or one side is darker than the other.
Two different-looking faults, one control. Both are the printhead pressure toggles, and setting them costs nothing, needs no tools and can be put straight back.
Which is exactly why it is the first thing to try. Everything else that causes these means taking the machine apart.
Two toggles, and a scale moulded in beside each one.
Two on this ZM400. How many you have depends on the model — some industrial machines have one.
Start at the bottom and come up one notch at a time.
It is trial and error, and the order stops it being guesswork.
Wind both toggles fully left
Least pressure, both sides, every time. Whatever somebody set last month, you are starting from a known place rather than from the middle of their guess.
Try the right-hand side, one notch
Clockwise. One notch, print a label, look at it. One at a time is the whole technique — two changes at once and you cannot tell which one did something.
Still not right? Now the left one
The left toggle takes the left side of the label. So if the left of your print is the weak side, that is the one to bring up.
You should not need to go far. Four on both sides, or wound fully right, is extreme and is usually unnecessary. If that is where you have ended up, the pressure was probably not the problem.
Nothing here is permanent. The scale is there so you can put it back exactly where it was.
The other reasons, in the order worth trying them.
If the whole label is light rather than one side of it, that is speed against burn temperature and both are free to change. The scale runs 0 to 30 and most stock prints well between 15 and 25 — when it prints too light →
If the ribbon is loaded the wrong way round, nothing you do to the pressure will help, because the ink is facing the printhead rather than the label — how to load one, and the three ways it goes wrong →
A bowed printhead also prints light down one side, and it is the one that needs the machine apart rather than a thumb and two minutes. It is usually the result of over-tightening a head on the way in — printheads, and how to pick the right one →
A sharp white line down every label is none of these. That is a burnt-out element and the head is finished.
We have these on the bench.
If you would rather not poke at a printhead on a machine you depend on, that is a fair position and we will talk you through it — or look at it properly if it turns out to be more than a setting. Zebra service and repairs →
0414 53 53 95, or andrei@barcodedatalink.com.