A pretty 1960 reissue Les Paul in for a setup and broken tuner knob.  Gibson Deluxe tuners are a fairly delicate tuner when compared to others.  A common issue is that the rear covers can become loose over time.  These tuners were fairly tight but the D string tuning knob was failing from a previous repair.  The knob was cracked and glued by the player, but the glue had begun to fail.  In the video below from the vlog, I was able to open up the knob and work some super glue into the break before clamping it closed.