Quote Originally Posted by matt4x4
If you can, this sometimes also helps - screw the male fitting in as much as you can, this should open the gap (crack) some, spread PVC glue all over the broken area, unscrew the male fitting and then put on the clamp, the glue should have gone in the crack some and should be helping with sealing it - especially if the crack went beyond the threaded area.
This definitely works well. I was able to open the crack up enough to use some AquaMend putty-type glue even while my multiport was wet. It held up for a complete season, and probably would have held up this season too but I got a good deal on a replacement valve.

-Chris