Go to Edmund Optics and purchase stock number #52-105. Use forceps, and fold the paper so you always have a clean side up. Apply a little 92%+ Isopropyll (should be easy to get 99%) and you can get any reflective surface streak free with almost no issues. Thank me later ;)
Use 5555. You don’t want to perform a calibration, and you shouldn’t have to. In fact you shouldn’t spend more than an hour on one of these if you’re more than a BMET 2. Send these out to Select Biomedical, or a similar company - they often do the repairs at a lower cost than you can find the parts, and they warranty the repairs. When I go into a hospital I count my inventory, then run it by my usual support companies to have them bid on the service. This gets me competitive pricing on repairs that make it simply not economical to do it yourself.
It doesn’t seem that info is very intuitive. The problem is your ventilator was previously interfaced with a physiological monitor, and is either looking for vitals from, or trying to send vitals to this monitor. If you call me I may be able to walk you through it.