Wow, I'm very impressed with Bill Pye. He pointed me in the direction of the reed valve's. sure enough there was the tinyest of gaps where one of the valve's sat. bit of cleaning, turned it over and its working much better. I'm pretty sure there was some crap on the other valve so thats being cleaned after the weekend. He did say the valves are no longer available so it's been a bit of carefull work not to bugger them up. Still I can't recomend Bill enough. thanks to this site too. P