The seat in my tipper is ridiculous. I am height impaired, so its as high as will go with the front tilted forwards so I can reach the pedals.
Thing is, slightest bump in the road or when I’m breaking and I’m up and down like a ■■■■■ kangaroo. I hit a nasty pot hole the other day and I swear I saw the flag on the moon it really is that bad.
I have tried all the levers and buttons but can’t get it to go solid. Anyone else had this problem?
Usually the cable is snapped or stretched. Remove the seat base then move the seat lever for the uppy downy piston so you know what you’re moving, push the piston in the direction you want (hard/soft) then replace seat.
Mine does the same when a limper gets in it 
Mine is also stuck in fair ground mode on our crappy old merc we have. I think the cable inside has come off or broken.
Sounds like the seat damper might be knackered. Pull the base of the seat and unclip the top of the damper, it looks like a tiny shock absorber. If you can push and pull the rod with ease then it’s fubar. Problem is i’m sure its a dealer part only and it aint cheap, from memory about £250.