A customer of TechnoRv Ordered a LED reading light (67-CW67) to replace a 1383 incandescent. The bulb base is the single contact Bayonet. When he received the new LED it would not work in the fixture, but it would work in another fixture, and his old incandescent worked in the fixture that the LED would not work in. Seemed a bit confusing as the problem did not follow the bulb, nor did the problem transfer to other fixtures.
The RV industry can be a little confusing at times.
With the incandescent light that was installed at the OEM level in the past , nobody was putting the wires at the same place all the time because the element (Incandescent) was working on both sides on the wiring installation.
Enter LED lighting and you deal with polarity. The reading fixture that he was trying to install the replacement with the 67-CW30L is polarity sensative, so the positive needed to be at the end of the bayonet and the ground on the round metal base to be able to work the proper way. I asked the customer to swap the 2 wires behind the fixture and the LED worked. Happy Customer!
Also, the wedge base LED's are polarity sensative, but that is easy, you just push it in, and if it does not work then turn it 180 degrees and reinsert and it will work.