From Bruce that sent me a copy of a jap link that showed how to do this but the description was unreadable so I had a go with only the pics to go from but here goes with my own pics and description
start by undoing the four 14mm nuts that hold the seat to the runners on the floor of the delica

then remove the seat from the delica [take great care as the seats do weight quite a lot]

next lay the seat on its back so you can acess the seat base and undo the four 12mm nuts that hold the metal base to the seat

if you now look down the side of the seat you will see two 14mm bolts that hold the seat back to the base remove these

now get some pliers and remove the R pin clip from the release linkage

and remove the R pin clip that is just below were you have taken out the last one

you can now with care pull the seat base down away from the seat

you will now see four bolt around the out side edge of the center turn plate on mine they were 5mm allen key bolts but on bruces jap copies they look like 12mm bolts

slacken off two bolts on one side but do not remove the bolts yet

remove one of the two loose bolts

then you need to lever up the plate that the bolts go through and place a washer under it in the place were you have removed the bolt
then refit the bolt lossely and remove the other bolt and repeat with the washer you can now do up the two bolts that side and repeat the process on the other side of the turn plate you can now in revese order put the seat back together and refit it to the delica

I hope that this was some help to you all? And thanks again for all the info bruce. :D