I have undertaken the task of stripping off 90 years of paint and stain (and now I am wondering if the goo at the bottom is actually a kind of wax). I have been using a heat gun, and then sanding (first trying the citrus stripper was a mess, although it is looking from my reading here that I should try it again after using the heat gun, which worked very well (except I have to do more sanding since it blistered the balasters, which were ok, and the molding on the other side, as well as the risers).
Anyway, I first had a square palm sander, which I didn't think was all that great. I bought a random orbit sander, which is working pretty well where it can reach. But for getting into the edges, I'm wondering if one of those little sanders (almost looks like a mouse, but apparently has different attachments like finger and small disc). I've seen one by B&D. But I'm wondering if it really removes much, and gets into tight corners and around the balusters. I know I'll continue to have to do some hand sanding, especially into the coves under the edges, but this is a big, long job. I've been at it for a while now, a little at a time, and want to see some nice clean, newly painted risers and trim, and stained treads, as well is be finished with the sanding mess, soon!
I'm trying to get down to bare wood (I'm ok with some imperfection due to age of house) as I want to have the option of staining rather than painting.