Hey guys. Few weeks ago I bought a bass guitar. It was an almost unused Yamaha RBX 170. This is my first bass guitar that I wanted to play every now and then alongside my other guitars. While it was in almost pristine condition after first tuning and playing the bass for roughly 10 minutes the nut cracked under a string slot and was immediatelly pulled back. Mind you, this guitar has got a nut at the end of the fretboard and doesn't have a nut slot. The original nut was made out of cheap plastic and had (I think) slots slightly too narrow for the strings, which might have been the cause of damage. I decided to replace the nut as I was able to get my hands on a precut NuBone nut that fit the specs of the old nut. Almost. I sanded the new nut to proper height leaving it a bit higher, for fine tuning, but after fitting it in the guitar I noticed that there was extreme tension on the contact point between the strings and the nut causing the strings to pull it towards the headstock. Took another look at the old nut just to find that the slots in it curve down towards the headstock. The new one accomodates the strings much better, however from what I've heard it should rest in place after tuning, without putting any glue on and it simply does not as the strings are pulling it out of it's place and even lifting it slightly. Is there a fix for this? Should I file the slots the way they are in the original? Could I use the strings wrapped in 1000/600 grit sand paper to achieve the curve? There is no luthier, music shop, guitar tech in my area, so I'm on my own, only with access to basic DIY tools.