How the hell am I supposed to adjust this? (Fender Duff PJ)
Remove the pickguard or use a ball-end wrench.
Yes, that’s a ball end wrench and should work, @akos . . .
I have no idea why Fender provides such poor access to truss rods on some of their basses. Feel happy you don’t have to take the neck off to get at them; some models do require you to.
Probably a tradition vs innovation thing…
Usually you get Fender Hex Allen Wrench with your guitar. For me it’s not a big deal if it’s up or down the neck. With a ball-end wrench you probably don’t have to remove your pickguard (depends on model). I prefer behind the nut too.
A bigger deal to me is that some truss rods connections/grips are horrible. I tried to adjust an Ibanez truss rod once and it was almost impossible to get a grip. I had to order a special size allen key to get it done and even then it was a close call…