Letter on position 1 (r) changed: 9 words bums fums gums hums lums mums sums tums vums Letter on position 2 (u) changed: 4 words rams rems rims roms Letter on position 3 (m) changed: 7 words rubs rucs ruds rues rugs runs ruts Letter on position 4 (s) changed: 2 words rume rump