Recently, I purchased a preowned 2004 Fender American Stratocaster Deluxe 50th Anniversary (Left handed) off eBay. The neck shows an up-bow. There is a relief of at least .015" at the 7th fret at the bass-side E string when doing a Fender relief check (the 1st and 17th fret being pressed down). Following is the issue when adjusting the neck: The truss rod nut is at least as worn as the original 1/8" Fender allen key it came with. Loosening the truss rod is no problem but tightening it is. When attemping the latter, the allen key will simply slip off. The truss rod itself seems to be very tight already and can't be further tightened especially with the nut being as worn as it is. I have been told by a luthier and a guitar technician to either return the instrument (in progress) or get a new custom-made neck by Warmoth, the latter of which presenting other difficulties (lefty 50th anniversary) and inconveniences. I have heard there also to be the option to surgically replace the nut adding a few washers in the process to potentially allow for further tightening of the truss rod. What are your experiences with this method, and how would you assess its rate of success considering my case here? I would like the neck to be almost perfectly straight for a proper fretjob and setup, with the bridge being flush with the body. I want to get to at least a Fender spec-level of relief (.008"-.010").