Just checked my 727-100 another company RE V2.7 for the Little Black line under the slats.
I don't have it,thought it could be a single one of those Little Blck antenae that are place in front of the slats on some planes ? Even if I extend the slats. I made various attempts at making it show, to my knowledge it didn't show,On the other hand I made a search and it could be a Static discharger like these on another plane scroll Down a bit for a Picture:https://en.wikipedia.org/wiki/Static_discharger Wonder if it's not a corrupt BMP you have and need a complete reinstallation of your CS727,If it persists,even if it doesn't bother you you could download a new copy.Berlopez