The blue piece had always been loose. And drops easily. Didn’t noticed it drop as I was on my way to class yesterday. Unfortunately, couldn’t find the piece as I retrace my step.

RIP. Had it since my practicum days… time to buy a new one.
Bought this years ago… with other tools for this chapter is a stethoscope (which really works!) and an oxymeter (clipped to finger to measure oxygen level and pulse rate). Those were the days being a young, enthusiastic teacher 😛

Oh, btw this model is the same size of a typical child’s heart.