If ive changed the fluid due to the steering been a bit heavy when turning so i drained reservoir and put new o rings on fitted it all back together bled it and its still heavy could this be the pump is nacked and not putting enough fluid to the rack or could it be the rack any one its baffled me ???

 

Try bleeding it again. Have you checked the obvious like tyre pressures, siezed track rod ends, siezed u/j on column. Try disconnecting track rod ends and see how it feels then, If its still heavy its either the pump or rack. The pump usualy gets noisey when its on its way out and the rack tends to get lighter. Has the vehicle been kerbed? that can damage rack and make it feel heavier. Hope this helps you.