Krivers, the hidden ones are the firing pin and top of hold open device inside of the frame. Also look to see if the inside is polished, not blued, is the muzzle blued or polished. DEEP pits can be repaired by TIG or MIG welding but it would add to cost of the restoration. Anything you do to a collection piece will probably drop the value if the next person that owns the gun knows it has been worked on. Minor pitting and gouges are best removed by mechanical and careful polishing IMO. My reworked Lugers are currently selling for around $1000 (I have sold 4 in the past few months at that rate) but most shooters will run $400-$600 and most collection pieces will run $800-$1200.Collection pieces I speak of are the standard Military models that were made in the hundreds of thousands a year. Value as a collection piece is usually double that of a shooter. My reworks are definetly shooters but seem to draw a slightly higher price because of condition and appearance. Thor
