I've got the above mentioned instrument in my shop for a setup and repair. The customer was having problems adjusting the truss rod. The serial # is 05050206 if that provides any useful information. I was able to get the truss rod nut out but it seemed to be at a weird angle. It was very difficult to remove. When I inspect the truss rod pocket hole it looks odd to me as well. The pocket has a greater downward angle than what I would consider normal. Now I'm having trouble getting the nut back in and threading onto the rod because of this angle. This was purchased used by the customer and he claims he was able to adjust the truss rod up until about a year ago. It's hard to know all the history since it was purchased used.
Ok, enough with me being overly wordy. Can anyone confirm the size of the truss rod nut and threads per inch etc. for this Korean made model? It's not 10-32 or 10-24 I've confirmed that. The adjustment end is 4mm. It does appear to be a 10 but without it threading onto a 24 or 32 threads per inch I'm stumped. Perhaps this isn't even the right nut and is something someone just jammed in there. Any information anyone could provide would be greatly appreciated.
It is probably metric and the measurement for the thread will be 'pitch' not 'thread per inch'. But, you can just measure the nut thread (I assume you have the tools to do that, if you have a repair shop).
probably the usual m5 with a 4mm wrench?