Thanks AVB, that is the deck alright but the exploded diagram doesn't show me the front section of how it raises and lowers. Anyway my mate has fitted a turnbuckle up the front so he could set the height in a fixed position so I believe it is working satisfactorily at the moment. It is just used to run over a few acres to keep the grass down to about 4" to keep the council off his back.
Thanks again for your help