Modulus truss rod issues

[Espresto]

I can't seem to get the relief out of my Modulus VJ's neck. It's playable but sometimes only barely, and I find this incredibly disappointing. I've maxed out the truss rod and tried lighter strings, and there's been some improvement, but not enough. What more can I do?

I have to be able to do it on my own, as far as I know there isn't a decent tech anywhere in the entire city.