Heidemann claimed that he responded to Kruschka's "Help Wanted" ad in the New Yorker Staats-Zeitung, New York's German language newspaper and that this was how he got his job. Armed with certain German words, I checked the Staats-Zeitung for September-October 1910, but found no such ad. (Admittedly, my German is not very good; and the old German typestyle used in the newspaper was a chore even to look at.)
I did, however, find the following ad in The Asbury Park Evening Press for October 5, 1910:
The interesting thing is that it said "Apply Couse" (which was a candy shop) but gives Kruschka's address. Couse Candy (614 Cookman) was right next door to Kruschka's. The ad may be in error or in fact be a Couse ad giving Kruschka's address (for some reason) as the place to apply to.
Through Heidemann started work at Kruschka's on October 2, there were (I believe) earlier examples of this ad. Anyway, I found the ad interesting. These kinds of fascinating (and frustrating) uncertainties are a part of doing research.