Update: I decided to replace the C9013 with a BC337 again after all this. When I plugged it in, the relay clicked, the LED came on and the slave sockets got 230VAC! Could it be that it was the transistor all along? I removed the series resistors and replaced the current transformer. With a load in the master, it now switches on the slave sockets like it used to. So why wasn’t I getting the correct voltages in the circuit while the transformer was installed before? If I had been getting DC Voltage to the transistor base when I replaced it the first time, why didn’t it switch on the relay? While I was messing around with the current transformer, I noticed that the trim pot was a little loose. I thought it was because there was a white plastic extension on it, but when I examined it closely with a magnifying glass, I noticed a loose solder connection. I immediately fixed this, but since the faulty transistor was still installed, it didn’t make a difference. I think the trim pot was messing up the threshold current, which wasn’t allowing enough voltage to get to the new transistor, which tricked me into looking elsewhere for the fault. Unfortunately, I put the original transistor back in the circuit because there didn’t seem to be a difference with the new one.
Doh!
When I plugged the C9013 back into my transistor test circuit, it passed again. Testing it again with the mulitmeter set to diode mode, I get no voltage either direction across C and E. The voltage between B and E is .602 but the voltage between B and C is .972. The collector is, of course, where the load is. I didn't think that voltage difference would be so important. Anyway, I learned something about testing transistors. Even if they pass basic functionality tests, you can't call them good until the diode test voltages are very close to each other. Thanks again for all the help. I'm sorry I wasted a lot of your time, but at least I learned a lot too and that’s what Dave is always preaching ;-)