Cleanliness is essential
Keeping your card machine clean is important if you want it to last a long time. Dust and other types of dirt and debris can enter through openings on the device (e.g. buttons, card slots) and reach the internal electronics, causing various malfunctions.
For example, poor hygiene can cause issues reading plastic cards. Cleaning is also essential to lower the risk of spreading germs.
As a general rule, just use water and soap on a soft and slightly damp cloth to rub the outside of the machine, as explained in most card terminal help guides. Do not use alcohol gel or spray any liquid directly on the surfaces.
Also be very mindful of how much water you use. Do not allow liquid to seep into the card machine, as this could cause the device to stop working.