Sounds like it could be that solenoid's come loose again, check it again. It's worth cleaning the contacts and putting a cable tie around it to hold the plug tight on.
If there was smoke, check the wiring around the solenoid / relay and around the regulator area for signs of overheating etc. If this get's really hot, it may give off a light smoke before it actually burns.
You may have a poor / dirty connection at the relay which is causing massive resistance and hence the wiring heats up and smokes (see that straw, I'm clutching it)