Maybe not. Mine is supposed to be locked too (the little key symbol is showing) but the trick is to not turn the knob until the machine is turned on and the little display door shows the pressure you are set at. Then you can turn the knob and adjust the pressure or at least I can with mine. Thanks ...

Thanks dsm. My machine does have the key showing, so I guess I'm screwed. More about making money than existing for the customer I guess. Hope I don't fall asleap and kill someone driving while I wait to get into the mother may I change my pressure people. I've only been on a CPAP for 10 years. I ha...

hello I'm new to this site. Not sure how to navigate it. I have the same model hc221le. I found the nobs as described. The large knob on the left easily pulls out and it appears to be some sort of port. The small knob to the left will turn but nothing happens. It will not push in or pull out. I trie...