Lunch, you are wise not to judge the skimmer yet. It can take up to a couple weeks for the plasticizers to get worked off of the acrylic.
As far as the noise on your RM skimmer, it is kinda hard to describe but there is a bit of a "choppy" sound coming from the air intake. From the sound, I figured it was coming from Sedra pump but it is definitely coming from the air intake. So far the skimmer still isn't producing anything. We will give it a little more time. Still a bit early to guess but I think the riser tube might be too narrow.