Thanks all. I emailed ProSus asking them how I could check the pressure (150psi) and all they told me was they could rebuild the unit if I send it to them and the price would depend on what they have to rebuild...so I emailed them again, thanking them for what info they gave me (almost nothing) and asking again, how I may be able to check the nitrogen level.
Mike, the wobble has been there since I got the bike but has gotten worse as the miles add up. I've (felt) that the rear shock has been going away for some time now (which may account for the early tire wear on my rear tire last summer?) but have no way to check its pressure. Hopefully, ProSus will finally answer my question. I'll keep Klaus in mind.
It ain't the destination, its the journey...