al-ko LT250 cutting line and carby settings?

hi my name is david i'm having trouble with a al-ko LTt250
petrol strimmer could anyone please help the problem is the bump feed i've changed the cutting line but it doesn't seem
to work when you bump it on the floor could anyone tell me if there is any special way to do the line. i am also having trouble
with the carb setting it's a zama carb with 2 screws one high and one low i woud be greatfull of any help