The little contacts on the bottom of the socket are crimped onto each wire and threaded through the little fiber disk on the bottom of the socket. What seems to have happened with mine is that, with the bulb in place, the wires got pulled from the back, and so the wires were pulling the contacts inward so they were sitting low in the sockets. Here's what I would try:
1- Put a little WD-40 on the fiber disk to make sure it can go smoothly up and down, and
2- With a needle nose pliers, grab the contacts, one at a time, and give them some gentle tugs upward to pull the wire back up through all the insulation, and then
3- Lightly sand the contacts