Hi everyone im completely new to this forum and elliptical workout machines in general and i was hoping to get some advice on an issue im having on my unit. So i have a nordictrack 14.7 which recently started randomly shaking and vibrating. While running slowly it works great and smooth. Once you start to pick up some speed and run for a few minutes, the entire top portion of the unit starts to violently shake. I feel like when im holding the handlebars i can keep it someone stable, but ones i take my hand off the handles it just continues shaking.

Ive checked the immediate bolts around the machine to make sure everything is tight and also lubricated. I really dont know what to look at so any help, no matter how primitive would be greatly appreciated!

Thank you.