Problem with structure in 3d printing

Welcome I have 3d printer Vertex and I have such issue. When I’m trying to print something i have structure of printing like on photos below. I thought that it’s fault of extruder (header and motor) so I replace onto net the same type. But it is occuring also. It causes that structure is very weak and easily can be broken. I do not what should I do could you help me?

imgur.com/yXjyGFM
imgur.com/a/cTs28
imgur.com/a/nBtmG
imgur.com/a/yR1h7

Dear mopsiu50,

it seems that you are at the same dead end like I was some time ago. You can search different forums and do a lot of experiments like I did it in the past. Therefor I summarized my experience in an small blog which you may check: ddd.k8400.hoehnemann.net.

I hope it will give you some new ideas. I would appreciate a feedback and possible improvements in case it was helpful.