Older style Liftmaster photo eye sensors had connectors attaching the the wire to the sensor. Since these sensors are generally located in a damp location in the garage, the connectors are prone to oxidation. This condition will result in difficulty closing the door. The use of marrette style wire connectors does not stop the wires from corrosion. The newer sensors do not use any connectors.
If it is necessary to join wires it is recommended that they are soldered. If you have any concern about your garage door opener, give us a call at 604 945-7595.