Tuning issue (including breaking a string)

Canadian Dulcimer Boy
03/28/22 05:47:39AM

Hi all, I recently got an old dulcimer and have had a ton of fun learning to play it. However, sometimes when I tune back up to DAD from CGC I hear a single ‘PING” sound coming from the nut area. On one occasion a string broke. If it is an issue with the grooves in the nut, what can I do to remedy this issue?