When you say leaked, do you mean it's not closing and CO2 is passing through it when it should be off. (seen in a bubble counter as bubbles) OR it's leaking CO2 out of the solenoid?
My problem was failing to close when power was off and bubble counter was showing full BPS as if it was turned on.
my cleaning done earlier in this thread has solved the issue for now and solenoid is shutting off CO2 via PH controller with out any issues now. Need to monitor to see how long this latest cleaning lasts.
FYI I doubt my solenoid was installed backwards, since it came from GLA assembled.