Jerky movement on 3 point linkage

[Bluebilly]

I recently fitted a finger bar mower (Ford Ransomes) onto my Dexta and all looked good until I noticed the linkage jerking upwards after a short while, this was regardless of the position of the height of the mower off the ground, or the position of the small lever on the RH side of the gearbox (sorry, can't remember what it is called). Normally, without much weight in the linkage the hydraulics operate nice and smoothly. The oil was recently changed out, so it is nice and clean. Any ideas what it might be that is causing this jerky movement? It is almost like the arms are dropping and the system is moving it back to the set position, but there is no obvious downward movement of the arms.

[Brian]

Sounds like this is normal if you mean it remains in the same position but just jumps. The small lever should be pointing forwards for working with your mower, (Position Control), not downwards, (Draft Control) which is only used for implements working in the ground or tipping trailers.

The lift is leaking down slightly and the internal linkage is correcting it.

[Bluebilly]

Thanks Brian, that is comforting news. I don't really want to start digging into the hydraulics unless I have to as I have too much other stuff to get on with. I'm sure we can all relate to that.
The lever was in the forward position at the time. I guess I will wait until I get a chance to try it out cutting some grass and see how it performs in action.