I've done all of 2 dives with my new mask, and it leaks like a leaky sieve ..

It only happens when I look up and the water enters the top of the mask. Having examined it closely, it seems as if the top strap isnt quit tight enough.
However, The strap is as tight as it will go, so I need to move the sliding buckle attachment to the 2nd hole on the top strap. Has anyone else had to do this?
Secondly, do you have to strip the unit to clean the purge valve or is it just a case of flushing it through with fresh water every now and then??
TIA
I had the same problem in the beginning. You have to start tightening the lower straps first. They should be so tight that you get near a perfect seal with no tension on the top strap. then give the top strap a few tugs and you will have a perfect seal.
I found the spring tension on the purge valve too high so i just lift the skirt with a finger when clearing. Unless you have water leaking in from the purge I would leave it alone.