On my Black & Decker
I wish I could tell you where the screw is, but I can tell you this- it's going to be tricky, as you know.
Black & Decker makes these units as unserviceable as they can, probably because they don't want any lawsuits from people tampering with 220 live, nasty volts. Sometimes they use special tools, and manufacturing processes that makes it virtually impossible to disassemble a unit without damage- clearly indicating attempted repairs, and destroying the iron in the process, making it unusable.
The short and simple of it is that they're made as throwaways, and even if you can get to the potentiometer, you're going to find a broken support or switch piece most likely, and won't be able to get a replacement part (you can try to google parts for irons, but will only get the whole iron).
Wish I had better news, but I've been through this years ago, and ended up breaking the iron in the process of getting it open, and I doubt it's gotten any easier over the years.
My advice is to see if you can, hopefully, get it open as far as you can, and see if you can somehow free the jammed arm. Otherwise, buy a good used or new one.
Wish I had better news, but good luck.
