Service Manual and Halogen Lamp Voltage Specs

Good Day To All I have a Microlab Instruments model ARX-3 IN 1 Chemistry machine that has an error of "Insert Flowcell properly or checks for air bubble/blockage in flow cell" This will occurs when I will sip distilled water after selecting parameter like CHOL. WORK DONE: I check the waste pump- normal I check the tubings for a leak- no leakage I check the lamp- It has light I check the flowcell- I don't sure if the position is correct So I need your help to fix this Chemistry machine, base on the error that will pop up when I will sip distilled water as a baseline. And I will ask also for a service manual for this model. Your help is valuable and very appreciated. Thank you so much in advance.