It may be the star ratchet that needs replacing. If you've had any "skipping" of the freehub under load, then I would suspect this is the case. Unfortunately the Hugi require the use of bearing pullers when servicing. They sell a tool to service their hubs, but it WHOLESALED for $80, so I just said NO! If your LBS doesn't have the proper tool, they won't be able to disassemble the freehub body or pull the worn cartridge bearings.
I've gone through three DT/Hugi hubs on my mtn. tandem and have had enough with the newer, quieter design. (The star ratchets blew out under high torque.)
However, the older Union/Hugi design has lasted over twelve years on our road tandem, so if you have that one, I think it's worth reconditioning. And I've had good luck with the Hugi Compact on my single, but I think it's the Union Hugi as well.