Old furniture is to be taken apart, repaired and reassembled must be marked so that the pieces can be easily identified. Since surface marks will be obliterated by stripping and refinishing chemicals, it’s best to use indentation marks.
Mark all pieces before disassembly and always on the underside. Mark only one end on the tenon close to the mortise. Use one set of chisel marks with the grain and then one set across the grain.
Another valuable tip to aid you when restoring anything you can imagine and I’m mainly referring to machinery here, take photographs before you dissemble..
Removing Broken Screws
Bore out a hole with a plug cutter around the screw shank, if the screw is large and runs deep and cannot be snapped with the plug,, chisel away the plug and grab the shank with pliers. Be careful not to damage the rim of the hole, once the screw and plug are removed, you can fill the hole with a plug made with a cutter two sizes larger than the one used to cut the original hole.
This method is better than using a dowel as a plug because the fit will usually be much tighter, the plug will be less visible since it’s grain will match that of the original piece, and the screw can be resunk across grain stead of into the end grain of a dowel.