I don't see the same adjustment through the vents. The tower on this model has a sort of transparent, green, triangular cut-out that moves slightly: I never really knew what it was for, but I find, in some instruction booklet on line, that it was a "ramp" control, for people who need a lower pressure when they're first falling asleep. (I never really felt much need for this; indeed, on later machines, I had such a function, and tried it, but didn't really like it--I'm just as happy with the full pressure when I first put the mask on. Maybe I'm just used to that, and it feels peculiar to have it any other way.)
Anyway, there appear to be little "seams" at the top of the tower, as if there's some straightforward way of opening it up like the lid of a box. I imagine there must be some sort of control similar to the little white screw on the earlier model, hidden in there, but I'm pretty sure it isn't accessible in the same way, directly through the vents.
If anybody knows how to open up THIS model, as well, so I can bring its pressure up to where it should be, I'd be very grateful for step-by-step instructions!
I've used my oldest Respironics machine for about three nights now, and it's doing the job very well indeed. It's my very first CPAP machine, from back in the early 1990's, I guess--CPAP therapy was quite new back then, about seven years old, I think--the motor had been replaced once at some point. I'm very delighted to have its life extended, thanks to the Apnea Board Forum!