Ok,thanx for the help.Ive fixed it now.
Rang elektron(they picked up straight away)and they said its a dirty lens ect.Well i gave it a quick blow ect and now its fine.A good way to test the slider is to turn on in test mode (turn on with function down)press test and move the slider .itshould/will run along the lights on the track trigs-back and forth.ha ha.Now i can have fun: ]