Automatic problem

I have got a disco 98 td5 auto and need a little help. It will not pull of in D any more we have to select 1st and work up the gears until speed is reached then it will stay in D until the car vertually stops then we have to select 1 again and go through routine again. Reverse works fine and i have checked the auto transmission level via the bolt on the front of the sump and it sprayed everywhere so believe there is plenty of fluid which is a red colour so also think it is in good condition but dont know what to try now as haynes manual wasnt worth the money to buy as it just says to take to dealer

Any help would be much appreciated

Many thanks Stuart

have a read here Ashcroft Transmissions - 4HP22 FAQ's

i would find good local specialist in zf autos as usually its just one way clutch or a clutch pack that fail and the rest of box is good ,usually during rebuild very few parts need changing in most cases,you do get worse cases but diesels are heavy on one way clutch

thanks for quick reply have looked on the link from martin hollins and it looks like sprag clutch?? happily if it is that it says the landy can still be drove unhappily i am not massive auto box fan so if any one knows of any specialists in wolverhampton/b-ham area would be grateful

sprag clutch is one way clutch or free wheel clutch .located in clucth pack c-d

thanks for replies will get some prices monday, just a query is it a hard job to do time is not an issue as my wife car can be used i just dont want to make anything else worse if it is too hard!!