#1
ok i was restringing my guitar and i was wobbling the nut then i heard a crack i lifted the nut and half of it is embedded in the bridge what now?!!
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#2
By bridge nut im guessing you mean the saddle. If its cracked the only choice is to get it replaced. You can do it yourself but if your at all worried you should get a qualified guitar tech to do it. Take it into a shop n see wat they say.