Di vessel vibration

Hey guys after some help please ,

So I've just switched from a small van to large transit everything went in and works as it should , however I have a vibrating feedback from one of my di vessels ???

I have double di setup

First di hoselock and hose back to pump vibrate terribly what could be the cause or solution please ???

Just to clarify its all fitted in not against any wood or loose anywhere

Sent using the Window Cleaning Forums mobile app

My first hunch is it pulls in air somehow.