I just spent some time helping a student find some early modern texts. S/he'd "looked" but hadn't found many on the list s/he'd put together from another resource of texts that might be useful. And so I helped.
There are tricks to finding early modern texts. You have to be willing to play fast and loose with spelling, and switching "v" and "u" typographically (along with "i" and "J" and "w" and "vv"; the name "doubleyou" makes a lot more sense when I think about "u" and "v" being different back then.)
But the most important trick is that you have to be willing to try this and that in different ways; you have to be willing to bang your head about the search engine (and praise be for search engines, because it's softer than banging my head against a card catalog!) for a while.
I know my students have to learn to be persistent about research. But these are the same students who probably parse their dps in WoW or tell me the exact ERA for their favorite pitcher or tell me exactly which shade of nail polish J.Lo wears. The information they care about, they'll put in the time to find or figure out.
The good thing is that I get to feel a little useful.