I have been using the Medtronic 640g Insulin Pump for five months and I have had a problem with bubbles in the tubing, some are small bubbles but this seems to be getting worse, in the past 12 days I have had at least 6 large ones varying from 9cm to 19cm, The healthcare people don't seem bothered, I would like to know if anyone has had this problem, surely it is not normal, I am continuously checking the tube. I was previously using the Animas Vibe which never caused any problems. Thankyou Sheila