\version "1.3.146"
-stemUp = \property Voice.Stem \override #'direction = #1
-stemDown = \property Voice.Stem \override #'direction = #-1
+stemUp = \property Voice.Stem \set #'direction = #1
+stemDown = \property Voice.Stem \set #'direction = #-1
stemBoth= \property Voice.Stem \revert #'direction
slurUp = \property Voice.Slur \override #'direction = #1