... a problem we should all have if we're lucky. Your '61 stack knobs J is a Holy Grail of Grails with its custom color, matching headstock and intact string mutes. I also noticed that your truss rod adjustment screw is flush with the heel which suggests that the truss rod has not needed to be tightened much (or at all) in order to maintain the relief that you like and it has plenty of capacity to adjust if you ever wanted to. I had an all original sunburst '60 stack knobs J as well as refinished '63 and '65 Js back in the late 70's/early 80's when I was playing music full time and you could still buy what are now highly collectible basses for run of the mill used basses coin. Anyway, mine were good players, but all of them had thin necks (particularly the '60) and I had to adjust the truss rods regularly to keep them that way. I was basing out of Iowa and later Wisconsin and touring a 15 state area in the upper midwest as well as places in Canada so I was going in and out of hot/humid and cold/dry climates so that might have had something to do with the neck instability I experienced.