[Equipment] Help solving power issue (REMstar Auto A-Flex cycling off/on during use))

[RhythmMachine]

I have an old Respironics REMstar Auto A-Flex System One (series 50... 55X, as far as I can tell) that I use on occasion. Recently, it's been stopping (sometimes after running for more than 6 hours as expected) and giving a repeating beep-beep warning with a "Service Required" message on the screen. After that, if I unplug it and plug it back in it sometimes works correctly again (at least for a while) and sometimes just continues to beep and ask me for service. Since this usually happens in the middle of the night some of the details are foggy for me, so I don't know if this happens every time or only some of the times, but it appears to be very briefly turning off, booting up, beeping at me, and then turning off/on again, over and over. I've removed the memory card and humidifier as possible points of failure, but the problem continues to hit me, usually more than once per night.

I know that replacing the power supply is one possible fix, but here in Canada those seem to be going for over $100 which is more than I'm willing to gamble on this old machine. I've read that sometimes the connections on the main control board can erode and that it's possible a bit of solder in the right place could be all that's required to allow the machine to remain fully powered.

I should add here that this is my backup machine and I don't have a budget to replace it, so buying another used one isn't a good option for me. It isn't under warranty and repairs would likely cost more than buying an older one that's already working, so there's no benefit in going back to the clinic for help. I realize that the control board issue I'm suspecting may not actually be the problem, and even if it is I may just make things worse by digging in and working on it. If I can get it working with a bit of time and solder then it's a big win. If I can't, I'm not much further behind than I am now. Eyes wide open.

With all of that said, can anyone provide any guidance for where on the control board I should be looking for a likely connection problem? I have the schematics and the repair manual from the private files area (thanks!), but am not entirely sure how to interpret them. The image of the control board is attached.

Thanks!

   

[factor]

Service required vid.
https://youtu.be/v29ekeqo-l8

I would start with blowing all of the dust out of it. If it has any.
I would disconnect the connectors to the Motherboard and take it out and look for issues like discoloration.
Like in the video it could be the sensor is dirty and is unable to predict pressure so it shuts down.

[RhythmMachine]

Thanks for the suggestion, Brent! I opened it up and took a look... no obvious debris or discoloration, but I did notice what looked like either a one-way valve or bit of extra rubber on the bottom of the board where the sensors are, and I suspect it was sometimes blocking the flow and causing the issue. I removed it with tweezers and then tried for a while last night (ended up switching over to my Airsense for comfort since I was having trouble sleeping) but I've been running the REMstar all day today without a load and it hasn't shut off or errored once. I'll try it again overnight in a normal use situation, but removing that extra flap of rubber may have been all it took. I'll report back and post a picture of what I took out if that seems to resolve the issue.