I have had several DM/PM markers. My advice is that, if you do not have an issue at the moment, leaks and such, then all I would do is clean and lube the regs. Not really a need in replacing any orings unless you have an issue that can only be resolved by a new oring.
As another general rule, if you do not have any issues then chances are that the orings in both regs are good. On top of that they are most likely broken in and seated pretty good. All of this add to consistency, whitch is a good thing.
Orings in general usually last a very long time. Sometimes you may get some dirt or debris in a reg/bolt assembly that can/may cause an oring to be sliced or cut and result in a leak or failure to funtion in what ever regaurd.
With all that said, if you still feel the need in changing the orings you can find full a full break down of the marker in the stickies. Go to the stickies and look for the link for the manuals. That link will take you to a thread on here with all the manuals for all the DM/PM markers from about 06 to current.
Just my .02 cents.
Too many markers, not enough time.
Every man dies, not every man really lives.