Stethoscope help

My mother is visiting us and she has dangerously high bp. The Dr. wants me to take it frequently. I have an electronic bp cuff but i know taking it with a stethoscope provides more accurate results. I am not in NS yet, but learned to take bp in our physiology class. I thought my mom would be the perfect one to practice on while she is here. I will still use our electric cuff but can practice my skills with the other.

So, I ordered, through our pharmacy, an inexpensive stethoscope. My problem is I can't hear out of it! Since I haven't been to NS yet, I was hoping someone could give me the ins and outs of scopes.

First, what can i do to hear out of this scope? When i turn it to the small bell side i can hear a faint hb. I can't hear any lung sounds nor can I hear the blood rushing through the vessel. When i turn the scope to the large bell side, if i put my finger over the mini side, i can also hear a faint hb, no lung sounds and no blood.

With that said, it is a very inexpensive scope so which scope is the best of the best? Is this a common thing with cheap scopes? It might end up a toy for my kids!

Thank you for the replies. I am most impressed with the response I rec'd from my other post. Thanks!

MammaNurse2Be