LED Christmas lights

Well, they're actually called "berry lights" They are powered by 2 C-cells, and have 20 "berries" on the string. I bought a set for $2.47 at Walmart, and as soon as I got them home, I tried them out. Some of the LEDs were dimmer, and flickering a little bit. Wiggling the berries helped a little, but not all that much. I took one of the berries off (they unplug like regular Christmas lights) and proceeded to take it apart. The berry is molded directly to the LED, so I had to break it off. The LED is small (smaller than a standard LED--maybe 3MM?). I was hoping the LEDs were nice bright white ones simply covered with a red berry shell, but nope. Oh well. I guess they still can serve a purpose, even if they aren't very bright.

I think I have two sets of those from last year. Mine also fade from the battery end to the far one, I suspect it's because the wires used are so thin that there's a significant voltage drop from one end to the other.

All I'd like to know is whether the socket used is a standard one, as I'd like to be able to salvage the LED's from the two chains I have, as they are both dead, fallen apart.