yeah, getting there. Thanks for your help. I will try the mylar alone next. However just to clarify I did not use the the two diaphragms with flaps. Only the conventional has flaps. The mylar part I used is the one at the bottom right in the photo. That one on top of the conventional one gives me the shape of the mylar diaphragm with the tick (which I haven't used yet) in the picture.
The problem the cutter must have had to do with the leak, The metering diaphragm was broken and a bit stiff. I replaced it and the leak has gone. I was able to use the cutter for 20 minutes. The pump diaphragm is not broken but is is stiff and not good as you say.
