The drifting of the tubehead should only be corrected by

the dentist.
the salesman who sold the equipment to your office.
a trained repair person.
the dental assistant.

the dental assistant.

Rationale: the dental assistant – This repair does not have to be done by a trained repairperson as most often the cause is just a loose screw or fitting and can be either tightened or replaced by an employee who has basic knowledge of the unit. If the problem goes beyond the scope or knowledge of the employee, only then do you have to call in a repair person.