Anymore feedback on the GRX Medical Expert Cardiology CD-27 stethoscope?

I have to throw in my two on this one.. I bought the cd27 off of ebay a few months ago for a friend going into nursing school. he brought it back to me with some problems. So I took it for a test run. First thing I noticed was the rotating stem in the bottom of the steth was a little loose... and this concerned me b/c steths work on air pressurem, if this stem is loose it may not be holding pressure well. So first thing was BP, I could here BP sounds OK with the diaphragm... but MUCH better with the bell. Then did a simple cardiac exam on my buddy, heart sounds were almost imperceptible with the diaphragm and forget about hearing any abnormalities like flutter or a murmur. The bell worked very well again. I am inclined to believe this scope is defective as the diaphragm just doesnt work very well and is not sensitive whatsoever. From reading other reviews it seems I am the minority in getting a defective scope.. That being said, GRX has been VERY helpful in resolving the issue and is sending out a new scope to replace this one, I am very happy with their customer service and they really do stand behind their products as they say!