Repair and Maintenance Symptom A. One of the fluorescent tubes fails to light Reverse the tubes (see User Guide for instructions). If the same tube fails to light after being reversed, it can be assumed that the tube is defective and will need to be replaced. In the USA spare fluorescent tubes may be ordered from Stereo Optical (Tel. Nr. 800-344-9500). If the tube lights it can be assumed that one of the two transformers has failed, and will need to be replaced. The unit will need to be sent in for repair. See Warranty page for instructions.   Symptom B. Both fluorescent tubes fail to light It's very likely that the main on/off switch has become inoperative. The unit will need to be sent in for repair. See Warranty page for instructions.   Maintenance Changing Fluorescent Tubes The PAL-ID contains two (2) high intensity fluorescent tubes, which are available only through the exclusive distributor who supplied the unit. These tubes are not available through electrical or lighting fixture vendors in the USA Replacing one or both tubes. Disconnect unit from line power (remove plug from wall outlet). Remove all four (4) rubber cushion feet located on the underside of the unit,  giving access to four (4) of the five (5) phillips-head screws securing the upper and lower halves of the PAL-ID base. Loosen all five (5) screws completely. Return unit to upright position. Lift upper half of the base to gain access to fluorescent tube chamber. Pull out fluorescent tube, and replace. Replace and align base cover, making sure that no electrical wiring is caught between the edges of the two halves. Retighten all screws. Replace the rubber base cushions.