pete 379 interor light issues

There is a grey light manifold about the size of a can of snuff that has a mini bulb plugged into it behind the dash panel with the tractor/trailer air brake knob. There are several fiber optic light lines that are connected (plugged) into the light manifold. The fiber optic lines go to the dash marker plates and in essence light the mini tags. This was not one of Peterbilt's best design's. Usually 90% of the time the fiber lines get brittle, pinched or damaged inside the dash and can't transmit the light. Peterbilt want's around $300.00 to replace parts depending on what is not working. Suggestions, 1st, make sure mini bulb plugged into the manifold is working, 2nd if it is, unplug bulb from manifold and clean all the lenses inside with a Qtip and windex. You would be shocked how dirty it gets behind the dash. 3rd If fiber lines are broke or severed, replace. This is quite a job, you have to re attach all the lines to the panel while working around the dash switches and wires back there. That is why most of them that quit working rarely get fixed. A Peterbilt engineer brain fart for sure! Good luck!