Sliding door alignment

[Foxtrott]

Just picked up a 2018 transit custom... but ive noticed the slide door is a little dropped at front.... when I slide it shut it needs a good slam and in doing so it lifts a little - however this lift isn't enough for it to line up correctly with the shut lines of the van.. maybe need to come up 4mm (i think the rear could do with a little as well but this isn't obvious).

Ive looked around for how to adjust and it looks like this is all done on the top roller bracket (the lower roller doesn't seem to hold any load and is just a guide . This bracket looks to be fully adjusted up on mine (there are oval bolt holes on the bracket attached to the door) - also the bolt between the rollers and door bracket is tight (when this is loosened the door seems to drop).

Any advice welcome - is this a common issue - would a replacement top roller potentially resolve the issue. Also how do you adjust the rear end of the door?... this looks straight forward on a transit but not the same on a custom.

Cheers