I have a bath faucet which I think is a cheap Delta unit. It was installed about 2 years ago with the anticipation that the whole bath would be renovated soon. I say cheap because it is mostly plastic. The shower rarely gets used and now that I need it for guests arriving this weekend the shower diverter won't turn. It is the center type diverter between the hot and cold valves. I got most of the diverter apart but the stem is still inside the housing and I can't get it out. Nor will it turn. It is plastic and there does not seem to be any flat sides which to grasp with a wrench or socket. It seems as though it should just pull out. Any ideas on how to get this thing out?

Thanks,

rob