There is a procedure to check the level, not near a computer right now so can't describe it properly though.
TBH you may introduce a problem by doing that - I would only really recommend changing the fluid when replacing the accumulator or pump (should really do both together anyway).
When left alone (and driven properly) they are actually pretty reliable.
Leaks kill them, some are spontaneous, many seem to be due to someone fiddling.
Also, people driving them like conventional automatics (cooks the clutch, clutch actuator starts to leak, introduces air & muck, knackered seals, rediculous quote from "expert" who hasn't got a clue what he's looking at, stunned disbelief, game over)