Got a Gretsch 5420t last week. Couldn't keep it in tune to save my life. Talking five tunings everytime I play past 30 minutes. Very small use of the Bigsby. So I googled it up and found this forum. A combination of stretching my strings and lubing up my nut with some graphite seems to have solved the issue, but my question is, How often is lubing up your nut neccesary? I generally change strings every 2-3 months will that cut it?