Pretzer:
As I tried to explain earlier, the screws that you are trying to extract are not the entire issue. The “parting” bars inside your frame are rusted solid to the point that extracting them is probably not possible.
I have worked on 8—10 of these frames. Yours looks better than most and is certainly worth saving.
My recommendation is to drill out the heads of the screws just deep enough to clear the inside of the outer frame. At this point, the screws are no longer holding things together. Then try to gently separate the two halves of the frame.
This typically doesn’t work. The parting bars are simply not going to give up that easy. I have had luck by cutting the two halves of the frame apart- essentially sawing thru the parting bars. Then secure the frame half in a Vice with the end of the cut bar facing up. Then take a blunt punch about the same dimension as the parting bar and start driving it down into the frame. When it gets deep enough to allow a new parting bar to be inserted, the old parting bar is entombed forever inside your frame. You simply cannot reuse the old bars.
Use care to avoid damaging the thin sheet metal frame. Chances are your frame will need some repair. Typically there will be a few holes in the inner or outer frame channel. Instead of welding, consider filling the holes with JB weld epoxy, shaping it to the proper contour before it sets up. If you must weld on the frame, it takes skill and experience to weld the thin metal without making more damage. Proceed with care, it’s a valuable part.
