I have the profisix, which as far as body build goes, is essentially the same meter.
I had the same problem about 15 years ago where a few grains of dirt, or whatever, got under the clear plastic part that rotates. My bit of dirt got into the bottom area marked "LW V EV" well I've just checked it, yep there is some discolouration but everything is eminently readable.
At the time I took it to the official repairer and his suggestion was leave it alone and live with it. I gathered that pulling these things apart is one thing, putting it back together is another.
I've lived with it and the meter has had no ill effects.
Mick.