A lemur printer with Universal Paper Guide (UPG) has two optical sensors (optos) to detect the presence and position of the tickets. These sensors need cleaning periodically or when paper detection or positioning issues occur.


The follow needs to be done with the printer powered off and unplugged from the AC source.


Cut/tear opto

There is an optical sensor mounted beneath or on top of the paper guide rail. This optical sensor controls the ticket cut/tear position. Over a period of time there may be an accumulation of ticket dust on the optical sensor. This paper dust could cause erratic operation of the printer. In most cases cleaning off the optical sensor will resolve the above problem.


  1. Make sure power is off and the AC cord is disconnected from the printer.
  2. Using inert dusting gas or equivalent blow air over the optical sensor (see picture below).
  3. The printer is ready to be switched on and resume normal operation.



Above image shows a SQ opto in the UPG paper guide with metal rails



Above image shows a SQ opto in the UPG paper guide with plastic rails. The red dot on the rail indicates on which side the opto is installed.


Blow air in this area. Between the upper and lower rails



Load SQ Opto
A printer using the UPG paper guide has a load SQ opto that is responsible for letting the printer know when it has paper stock loaded in the printer. Over a period of time there may be an accumulation of ticket dust on the optical sensor. This paper dust could cause erratic operation of the printer. In most cases cleaning off the optical sensor will resolve the above problem.


  1. Make sure power is off and the AC cord is disconnected from the printer.
  2. Using inert dusting gas or equivalent blow air over the optical sensor (see picture below).
  3. The printer is ready to be switched on and resume normal operation.


The load opto has a yellow dot on the side of the housing, it is installed near the print head on either the left or right rail. The above picture shows it installed in the left rail of a UPG paper guide with metal rails.



The opto is installed near the print head on either the left or right rail.  The above picture shows it installed in the left rail of a UPG paper guide with metal rails.


The load opto has a yellow dot on the side of the housing.