You say you're a newbie, Mechphil. I only recently graduated from that status. Do you know how to let down the power of the mainspring by holding the crown and preventing the click from engaging the mainspring? That should be the first thing you do. When the mainspring is completely depleted of energy, see if you can wind it. If it winds then but doesn't run, the problem is not likely to be in the stem and mainspring. (It could be, of course, but it's less likely.) If it still doesn't wind, then the winding mechanism is the first place to look for problems. I am a physician by vocation and a watchmaker by avocation, but I bring some of the outlook of the former to the latter. The most common misdiagnosis is underdiagnosis. It may well be that your old watch has more than one problem. Good luck!
--Eric