I am having issues with mt Himoto Viper XST Upgrade Edition.

It seems Lower Buffer Mount and Upper Buffer Mounts are just slipping on each other and my wheels are not turning.

I did notice the nut above these parts was loose so I tightend it not thinking what it mught be for when this problem started, now I can no longer undo this nut as it seems everything turns with it.

I am a novice at these things so any help would be appreciated.