my multitester gives me ghost readings and I have read that the calibration is calibrated or lost and I uncovered the multitester and I observe several trimmers identified with VR1-VR2-VR4-VR5 and VR6 I do not dare to move them because I do not know that modify someone will have an idea or know calibrate and can support or if you have the diagram I think it can also work. I grab any support in advance, help.