My hubby had the exact model you have. He used his from the spring of 2003 until September 2014, when he finally got a new sleep study for him (and a sleep study for me).
Really, truly, please get a newer machine. You will be AMAZED at the difference. The multiple pressures as opposed to the single pressure is SO much better; so much more comfortable and SO much better for treating the apneas.
We loaned the old single pressure unit (known as "the brick") to my sister to use until her machine arrived (took about 2 months for the DME to get their rear in gear, ARGH!). While "the brick" made a huge difference in her sleep, when she started using the new machine, a PR System One w/humidifier, she absolutely could not believe the difference the adjustable pressure AND the humidifier made over "the brick". It was so much better!
So, please, if at all possible, get yourself a newer machine; your body will notice the difference and appreciate it.
Diagnosed: 44 AHI when supine, O2 down to 82%
Treated since 20 Sept 2014:: 0.7 AHI, Settings 7-15, EPR on Full Time at Level 3
Better living through CPAP/APAP machines!