This afternoon, I got back with my plug and batteries and immediately set to fixing the kit. I got out the screwdriver and pulled the board out to take a look. Yep, the battery needed replaced. With a new battery and the headphones plugged in, I wired up the key and held my breath...
And from the headphones came sound!
It worked! The circuit still works even after all this time. Now I will finally be able to practice sending the code. I couldn't do it before because the clicking noise of the key doesn't tell you whether you just tapped a "dit" or held a "dah".
By the way, work did go pretty well. Orientation is always tiring, and I did get more paperwork to do tonight, but we did get a tour of the Library and I got to meet some nice people. The worst part of the day was walking home in 100 degree heat! Whew!