Anyone able to throw some light here? I am shopping a Blackwater 100. In the process of replacing the insert lamps with LED's, I ran into a problem where a lamp stayed lit at all times. Thought it was a bad 2n5060, but replacing that didn't help. The lamp sockets are the wedge type with a diode pressed into a slot on the back of the metal base and the banded side of the diode inserted into the end of the socket where normally a tab would be. I tested the socket and saw a short across the diode. Thinking it was bad, I replaced it but still a short! I had several spare sockets in stock without the diode installed but they showed continuity between the lamp metal base and the end of the socket with no tab (where the diode would presumably go). But one of the sockets which looked IDENTICAL to all the others but had a diode installed did not have this continuity.

Long story short, when I used the socket with no continuity and its diode installed, the LED worked correctly. With all the others, the light stayed on constantly. So...are there two very similar 555 wedge sockets made with different configurations? One with a diode installed and no continuity and one with no diode but also no tab on that side of the socket?