Thermistors, sleeves, and other replacement parts for fluidotherapy machines are available online and many don't require a professional to carry out the replacement. When it comes to thermistors, you must first make sure that the fluidotherapy unit is unplugged. You then remove the unit cover, locate the thermistor, pull it out of the mounting clip, and unplug the wire harness. Attach the new thermistor to the mounting clip and perform all the previous steps in reverse.