Oh Buddy. Bad news! Broken Truss Rod. This is an old Ibanez Rickenbacker copy. The neck is very long and thin, got a lot of upbow which someone tried to correct with a lot of force, and sheared off the nut. Fingerboard removal was hard because the truss rod extended into the fingerboard. Finally got it off, replaced the rod with a nice modern one, and glued the FB back on with some backbow to compensate for the string pull. You can see the feeler gauge spacers to hold the backbow. Came out fine. Did not have to refret it, which was fine because the whole fingerboard had a heavy coat of varnish.