How to adjust printhead gap - OKI MICROLINE 590 Matrix Printer

check
1- ribbon quality ( it might damaged )
2-Printhead gap - adjust the gap with the scaled arm aside the numbers related to the past thinketh ( no of copies)
3-ribbon mask ( metal plate in front of printhead - might be damaged)

Can you adjust the platen printhead gap? Printer Adjustments for Thick Papers Platen Gap

The gaps run in the direction of the label feed? You have a bad printhead. Bad dots on the printhead prevent it from printing your format in the areas that you see the blank lines.
There is no easy fix other than replacing the printhead. You can prevent (or actually prolong the time between failures) in the future by periodically cleaning your printhead. It's recommended that you clean the printhead after every roll of labels. The printhead is underneath the hinged assembly. Over time, ribbon or adhesive from the labels builds up and causes dots to go bad - creating the blank lines you see. Clean your new printhead with rubbing alcohol.

If I remember the 320, there is a head-gap adjustment that is normally moved for replacement of the head and must be reset again. Check your manual for that term; 'Head gap adjustment'

Hi, before buying new bits, make sure that the position of the printhead is near to the paper, there will be a 'head gap adjustment lever. hope this helps

Your labels are narrow, and might not be aligned beneath the gap sensor.

Remove the cover and make sure the labels are loaded all the way to the left (toward the inside wall of the printer.) There's a "label Guide" that keeps the labels from wandering to the right. There are two thumbscrews beneath the label path. The thumbscrew toward the back of the printer lets you adust the "label guide", which keeps the labels from wandering away from the sensor (and the proper printhead position).

Move the lever clockwise to open the printhead and adjust the guide so it is slightly snug against the labels but so that you can pull the labels without much effort.
The thumbscrew towards the front of the printer allow you to position the gap sensor to detect the leading edge and trailing edge of the label, so the printer can . If your printer used to work OK, this might be in the proper place, but if it is loose, slide the thumbscrew left or right to center the sneosr between the edges of the label.

Does it Error auto gap, if so it means head gap is out of spec?

If it is just displaying Auto gap, it means it is set for auto gap rather that manual gap.

Bad GAP HOME is a problem with the sensor (switch) that senses the automatically set printhead gap. Usually the wires break from flexing that run to the switch. Could be a bad switch also, or others.

You need to test the switch and wires with a meter.

The purpose of this adjustment is to set the PG offset value in accordance with the nose dimension
of the printhead. (For details, refer to Chapter 2.)
The offset for the nose dimension is represented by the adjustment value “ALPHA.” The “ALPHA” value
is stored in the memory on the main board, so the PG adjustment mechanism can read the value as
needed. Be sure to perform the adjustment when required. If this adjustment is not performed correctly,
the platen gap will be incorrect, the paper could be caught by a head pin, or, in the worst case, a head
pin could break.
NOTE: The printhead adjustment value is written on the front of the head unit (refer to Figure 4-2). After
the printhead is attached, the value cannot be seen. Be sure to write down the value before
attaching the printhead.
Step 1: Connect the AC cable. Mount the ribbon cassette, and load paper into the front tractor.
Step 2: Turn the printer power on while pressing the LINE FEED, MICRO FEED (V), and PAPER SELECT
switches (Be sure that the top cover is closed. Do not open it until you turn the printer power
off.), then wait until the buzzer rings five times.
REV.-A
Step 3:
Step 4:
Step 5:
Step 6:
Load the paper by pressing either the LINE FEED or PAPER SELECT switch, then wait until
the PAPER OUT lamp goes off (approximately 15 seconds).
(
Press the ON LINE switch.
Press the MICRO FEED (A) switch the number of times indicated by the value written on the
front of the printhead.
l The buzzer rings each time the MICRO FEED switch is pressed.
l Press the MICRO FEED (A) switch to increment the value.
l Press the MICRO FEED (V) switch to decrement the value.
l The value range is O to 10.
To confirm the value stored, press the FORM FEED switch so that the value is printed.
l If the value is incorrect, return to Step 5.
. When the value is correct, go to Step 7.
Step 7: Press the ON LINE switch and confirm that the buzzer rings five times. The printer prints the
final value stored. If the value is correct, turn the printer power off.