23 out of 44 is still reasonably good for a styrofoam incubator, my first incubator, was a styrofoam incubator, and out of 15 I got 2, I had read every thread on here about hatching, and it didn't help!! Styrofoam incubators are awful, afterward I just threw it in the bin, the next one I had was a 60 egg manual incubator, I got for £50, and it was ok, I used it for 2 years, and then I just sold it about 2 months ago, I'm going to save up, and invest in a decent one, at the minute, I have borrowed 2, an octagon 20, that I have 5 geese eggs in, and it is pretty good, I might save up, and get an octagon 40
and the other one I have, is a janoel manual 56 manual incubator, and the temperature is around 0.5oC - 1oC of a degree higher than it reads, but it is ok, but defiantly the octagon 20, is the best one if used so far
good luck on the rest of the eggs, be patient, some may just be late