Machine upgrade? advice please

Hi
I currently have the ResMed AirSense 10 AutoSet machine which I've had for 3 years. I also have spare hose, filters … a new tub and also the Medistrom Pilot 24 Lite battery for this machine. This CPAP device has become noisy AGAIN – a whistling noise on inhaling. It is cleaned regularly. Last time it became noisy I did lots of research and chose to replace the tub with a new one which is what is on it at the moment and this helped until very recently. This was less than 12 months ago. I’m tossing up whether to buy the same machine again (I normally get on pretty well with it) especially because of the spares I have or whether it would be wiser to buy the AirSense 11 which I believe is not compatible with spare parts mentioned above.
I’d like some advice please. What do people think is my best option. I am on an aged pension and with the cost of CPAP here is damned expensive. My private health cover (which is also damned expensive) will cover some of my costs. Any advice would be greatly appreciated.
Thanks and regards
Pam

First, why not replace the water tub again? Its not uncommon for the tub seal to begin to leak which causes a whistle. Note that under insurance these are usually replaced more often than once a year. The flexible seal that is squeezed between the bottom and top can leak. Also look to make sure that the tub is fully inserted into the machine, mine often whistles if its not completely inserted. I suggest you try pushing the tub in while breathing, if the whistle disappears you know where the issue is. You can also block the end of the hose where the mask attaches, run the machine, then carefully listen close to the machine to find where the whistle is coming from. An old mechanics trick is to use a piece of tubing in your ear then use the other end like a stethoscope to find the source of the noise.

But also. If you look inside where the tub is inserted there are two flexible pieces into which the tub tubes insert. The one on the output side is removable and replaceable. You should carefully inspect and clean both of these. If a replacement water tub doesn't fix the issue I'd replace the output adapter, they aren't terribly expensive and are pretty easy to replace (there are youtube video's showing how to do it).

Its unlikely that a 3 year old machine has failed, they normally are good for 20,000 hours or more, so 6 to 8 years.

I hope this helps.