I'm guessing it was made in the 80's when Stanley was pumping out tools. There was a thread talking about the lawsuit Stanley had because they printed USA on tools that were made overseas. I think the Master Pro is one of those.
It comes apart like the old Thorsens. There's a flat coil spring on the knuckle side of the head that needs prying off. Then the gear assembly slides out the back.
P.S. I'd love to see some pics of that 1/2" Master Pro apart! Number of teeth on the pawl and in the head would be great to know, too.
I will take some pictures when I get around to taking the Master Pro apart. I'll refer to the disassembled one when the time comes. Right now I have a few ratchets in baggies that I need to finish before I take any more apart. I confess, I am one of those who can take
anything apart. Putting it back together? Well, that takes me a little longer.
You may have seen in another thread where I was trying "KrudKutter" to remove corrosion and rust on an old Husky. It works very well but I left the parts in too long and some actually just liquefied, including half of the spring. I guess it will be a wall hanger until I can find another spring, if that's even possible. I'll go out to the garage and take some pictures of that one later today. Thanks for the tips.
EDIT: Bonneyman, I just went to take a quick look at the disassmebled round head Stanley and remembered that you had said the pictures were all gone. Sure enough there they are, gone! Any progress in getting them posted back up?