Try to unscrew the knob of the bleed valve out, there should be a white plastic washer inside doing the seal. The hole of the washer must have been widened due to excessive force used when closing the bleed valve. Just replace the washer and you will be back to business again.
My JB great white did the same I also thought it was the bleed vavle. It was the other side try to tighten the nut on that side. I removed mine there is a seal in there I wrapped the threads with Teflon tape been fine after that hope this works for you. Bob