I hope you can help me

I moved to my new studio with my equipment, bet there appeared some problem with my DeVibliss 4l Oxygen concentrator.
When attached oxygen pipe back to concentrator and switched it on, the level indicator first went up then quickly dropped down and then went down totally. Seems like when I attach the pipe to the corpus of concentrator it is leaking when not attached properly, but when I turn it untill the maximum, oxygen just does not get in to pipe, because there is no pressure as indicated by indicator, but when I remove pipe from concentrator, powerful stream of oxygen is hissing out of concentrator, even indicator goes up to maximum. I do not see any obstacles in pipe connector, what else should I do. I have switched it on and of 20 times, as well I have tried to attach and reattach pipe to the concentrator

Hoping for advice
