I've only used it on duck eggs, but think it should work with other eggs too. Didn't have the stethoscope with the quail eggs. One thing to remember is to turn off the incubator and the egg turner (if used) to cut out those noises. Don't forget to turn them back on once done (have done that once, noticed 20 minutes later). No need to lift the eggs. The stethoscope needs to be placed in the lower half of the egg, and you may need to find the side where the heart is closer too. Gives you a clearer louder sound. I usually mark the spot where I can hear the clearest.
Katharina