i think ive got a lazy turbo

[rooster 77]

ive got an 3ltr td 1997 e class 210, ive recently removed the head due to the heater plug being snapped off an had it machined out ,its all back together now an ive been using it for about six months an alls ok BUT the turbo seems to be getting increasingly lazy and seems an age to pick up speed is there anything i can do
cheers rooster