Are the sounds coming from the machine ok?

Hey,

I just assembled stepcraft 420 and got a question: while i do the jog, X axis works perfect, Y is a little louder and Z is making even louder and more weird sound(worse during going down). Can you please check the video on youtube and tell me if the noise is ok, or should I go to correct something(if yes, what)? https://www.youtube.com/watch?v=vnZgiZre8CA
Another sound is from the motors. Are they supposed to do some whistle noise in certain positions when machine is not moving? Don't know if you can here that on the video, but here it is: https://www.youtube.com/watch?v=K4YBAJUsm_4
Thanks in advance.