Thanks for the quick response. I have tried just what you've suggested - tilting the lid back at an angle, aligning the tabs and slots of the hinges, then pushing the lid in, but no luck. I've tried this probably 30 times in slightly different ways, different angles. No luck, so I cannot use the mac...

I have used a Resmed S9 unit regularly - with the H5i humidifier - for 3+ years. I have been impressed with its quality and construction, and have had no mechanical problems...until today. While I was packing for a trip the humidifier lid unexpectedly detached from the body and I cannot reattach it....