Iv recently bought a massey 7626 with front and cab suspension with the hydraulic damper system on the cab but it seems pretty rough on the road compared to our 6715s with front and mechanical cab suspension. I would of taught it would be far better I know there has prob been lots threads bout this and I know I could swap them out for shocks but I'm wondering if it's just the bottles that might need changing out like can they go hard over time? What's the best way to trouble shoot them? The unit in the picture can be purchased but you hav to buy the complete unit and it's 1100 aside from massey