I found the problem. I touched the leads of a test lamp to the housing and it blinked with the blinker on, and I ran test leads from a 12-volt source to the bulb and it lit. So, clearly the connection between the 2 is bad. I was able to order a new housing and a new twist in bulb housing from Amazon for under 30 bucks. They'll be here Wednesday and that should take care of it.