Doug,

Sounds like your accumulator N2 charge has lost some pressure.  As the accumulator pressure drops the useful capacity of the accumulator also drops. The "empty" precharge pressure isn't  listed in the manual but Ross would know. I would think that the precharge should be on the order of 100 to 300 PSI to give the best volume capacity.

Remember too that, because the accumulator "lives" at high pressure (~1100 PSI) it is possible for most of the prercharge to leak out at this pressure, leaving the empty precharge of less than zero.

After recharging the accumulator, do a leak test with some soap solution around the valve stem.  You can probably service the accumulator with the same equipment used for struts. Again, check with the factory on the details as I am just guessing.

Regards
Brent Regan