If you had a laser thermometer it would be optimal. Assuming you don’t, best approach would be 30 secs, then test it on something you don’t actually need to fix. Then let it cool, or re-heat it as necessary. After some tries you should have pinpointed the seconds needed for it to be OK.
Have you told dell you’ve been using unofficial cartridges? If so, I suggest you take the deal. Printers are made to break down if fed any toner/ink that does not come from the manufacturer. Since your model comes at a relatively high price, 60 $ is your best bet. If you try to do it yourself you will need that amount minimum for spare parts+a big chunk off your free time. It’s just not worth it.
If it’s indeed from this era, you might want to upgrade several things for it to run smoothly. It’s not prohibitive to just throw another drive with win10 and have it run, but performance will be poor. Good thing with desktops, however, is that you can always upgrade (I have my old tower from 2003 with new components, runs like a charm). If you want to put some time into it, you can build a technically new PC for less money than if you bought it pre-assembled. Around 400 euro should be enough to build a low end PC (assuming it’s for basic usage).
One possibility is that sometime when switching from assist control to control, the switch snapped and now it’s stuck on assist control. Your lab tech would be able to confirm/deny this and probably fix it. Since you are a hospital however (I am assuming), protocol suggests that you call your Philips Respironics provider for a solution.
Normally it is, happens on phones as well, due to normal wear and tear. You can try to open it up and reajust the usb port. However, you might want to backup your vital files from your drive. you can force your USB in with rubber bands, as a temporary fix just so you can back up said files. Then, proceed with the operation.