I took the main stat out to run it without it in but water just ran out quickly, I have tested that stat and it's fine. If there was an air lock surely the problem would have appeared before and not after 2 months and a thousand miles?
I did fit a brand new water pump but the gasket to the head was torn so I used some gasket seal as well. There are no leaks around it.
I have removed the bleed screw on the pump and water rises out of that so presume it's working, I haven't check the shaft/blades yet as it's a pain to remove them but that might be where to go next?
it depends - if its lower than the resovoir it may syphon out even if the pump is kaput
An option is to leave the waterpump on, with its shaft/ blades mounted, and just remove the plastic side cover
Alternatively, you could somehow check that the water is circulating,