The Type 89 mortar's Seasoned Crew SA + SNLF Captain's Pinpointer imply that the unit the mortar is attacking can only make a successful cover roll on a 6. But what happens if that unit is already disrupted (-1 penalty on cover rolls)?
As I recall, being disrupted does not cause a -1 on cover rolls, only -1 on attack rolls & -1 on defense. Units in the same hex have a -1 on cover as the target unit when attacked also, but being disrupted does not cause a -1 on cover rolls.