Stripes on the protective film of optical unit

Physical damage optical unit in form of stripes

When un-assembling the device and damage is visible in the protective film of the optical unit in form of stripes (or even smudges), it could be that the customer has been pulling and pushing the microplate reader too rough, causing splashing and following spreading of the liquid solution. It could also be that the customer is inserting/ejecting the microplate in an angle, causing scratching.