Skierg Rumbling noise

[Muffdiever]

Hey everyone.

Been a longtime C2 rowing machine owner of the model D, and just got my skierg delivered today. Mounted it to the wall, and noticed a few things compared to rower. When fly wheel is slowing down there is a light scraping noise which I dont hear on rower, but not when im pulling on the handles.

More importantly though, as I push the skierg to a sub 1:40 avg 500M it starts making a rumbling noise that gets louder and louder the more I push it and remains till wheel starts slowing down I assume above the 1:40 area. I've used a skierg before, and pushed it hard and don't remember this. The flywheel should more resistance noise, but not sound off balance. The skierg ive used in the past wasn't mounted to a bedroom wall, it was mounted to stand, but that shouldn't matter. Sounds like the cords inside are creating the rumble noise, but can't prove it with it mounted to wall.

Is there some adjustment or something I should check? Anyone else notice this? Any info much appreciated. Looks like a long weekend trying to figure this out...