Why is the touchscreen not responding correctly on the ElmaTear2 855?

Instructions for calibrating the touchscreen on the ElmaTear2 855, if it is not responding correctly or as expected.

The full instructions with images and diagrams are included in the PDF document.

Why is the touchscreen not responding correctly on the ElmaTear2 855?

WARNING: Any maintenance work undertaken on a James Heal instrument must be done so by a trained and competent person. Where electrical work is detailed, this should only be completed by a qualified engineer. James Heal is not responsible for damage or injury arising from work carried out by any person not qualified to do so. If in doubt, please contact James Heal or your local James Heal Agent