My model 3023 (2 years older than yours) has the monitor panel just below the sink and above the cupboard. Just hold the button for a status.
Quoting Bill from old 2005 post #5 :
"...you will know that the gray water tank is full when the gray water starts backing up into the bottom of the tub. The tub is the lowest point in the drain system. BTW, this is not nearly as nasty as it sounds, since gray water is not particularly dirty."
http://www.trailmanorowners.com/foru...anel#post19826
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