Since you're a beginner and your horn has just been serviced, suspect your technique first. It is critical to let the reed vibrate as freely as possible, especially on the lowest notes. An embouchure that is too tight or doesn't take in enough of the mouthpiece will cause the problems you're describing, and those problems plague beginning players. Avoid clamping with your jaw. Practice long tones, paying close attention to your embouchure and breath support. Start with notes you feel comfortable with, and as your confidence builds work down the scale. Here are some pointers for long tones. http://www-cs.canisius.edu/~bucheger/SaxPages1.html If you still suspect a problem with your horn after a couple of weeks of long tone practice, find a more experienced player to see if they have the same problem with it. The Bundy II is strictly a beginner's horn. When you get to be a better player you will want to move on, but it should suit your current needs if it is in good playing condition. Keep repair costs minimal, as those can easily exceed the value of the horn.