I just started my sprinkler system for the summer and it went well. First water came from under the bell but I restarted by a couple of times and then all water stoped coming out. But now there is a slow leak, maybe a drip per second. I tried draining the line, shutting down the water supply etc. but still just a slow leak.

Is this normal or should I replace the parts inside the bell housing. I'm pretty sure from some of the photos I've seen that this PVB is a Febco, but I don't know the model number.