Thanks for the info. From what I can tell, the tank is held in place by two screws, and sits on a kind of post that's attached to the fender. I'm assuming by "help" you mean you had to really force it off?
A couple other questions: did you have to replace anything when you pulled out the coolant sensor? It looks like there's a securing ring that may be difficult to get off without breaking. Also, there's a braided line right under the pressure cap; how did you get that off and back on?
I just submitted a partshop request, and will most likely be ordering the part(s) from here in a week or two. I've been accumulating a list of repair projects and parts over the past month or so, and after I prioritize them in terms of urgency and cost, will finish up my "research" and start tackling them. I'd be happy to post my experiences when I'm done with them.