NH 1114 Hydrostat Vibration

Last season my windrower started having a case of bad vibrations in the forward reverse lever on the hydro. Only seemed to be in road gear while slowing down and turning at the same time. I would describe it as excessive or harsh as the handle would violently shake from side to side. The manual says this can be normal if there is loose linkages. So I looked over all the joints and every that seems to be snug. This year I’m starting to notice it doing it a little bit while in the field, again while slowing down and turning. Almost sounds and feels like a chatter in the hydros. Turning direction doesn’t seem to matter but it’s always while slowing down. Anyone ever dealt with this on the older NH machines and could possibly help point me in the right direction. I’m stumped. My next step is new hydro oil and filter to see if that helps. Thanks!

NH 1114 Hydrostat Vibration