Xraangr, this might not be much consolation but most of us have found that when the lights do work they're pretty much worthless. See Carol's post above about that. Some folks successfully "clean" theirs periodically to keep them working. We've just given up and don't bother. We have had this unit long enough we know how long we can go and if we guess wrong then water in the shower and kitchen sink tell us they're full.
As for the black tank, we know when it starts to spit back I best empty it within 24 hours (of continued use). We get 6 to 9 days on the black tank, depending on how much we're in the rig.