Bernina Bernette Deco 600 , we are breaking way to...

Question

Bernina Bernette Deco 600 , we are breaking way to many needles. Sometimes it stiitches for 5 minutes or so nice and smooth then breaks a needle. other times we can do a complete pattern without breaking a needle. Theirs no lint build up and i cannot find any cause for this. Can someone give me an idea what is causing this?I have doulbe checked and we are using the needle called for by the manufacture, it is installed correctly and the cloth is a cotton flannel.