First we need to make sure there is a good circuit on both sides of the socket. It would seem that you have 12v at the bulb but as stated earlier in this post it sounds like a bad ground. Mine did the exact same thing you described in your first post, the reason that it is a little dim when it flashes is the ground is quite possibly open, so it is using another path to ground, like through another bulb, will also put two elements in series which will cause it to be dim, also to flash quickly. Check the continuity to ground first 'dog....stick with me, been there done that.