i did it when i got it and it worked fine, as stated earlier:

take the rubber cap off of the probe, rinse under lukewarm tapwater

open solution #7, put probe in and then move the screw until it goes to 7.
rinse in lukewarm water
next, take out the #10 fluid, put the probe in that and set it until it reaches 10

keep doing this until you can get it as close as possible