The route north of pt 1373 to Ngaawapurua Hut crosses private Maori land & the track is old & non-maintained but the ground trail is obvious as the track is moderately well-used. Note the swing bridge over the Ngaruroro River below the hut has been removed, however the Ngaruroro River can be crossed in all except flood conditions.
From the high point of 1373 head north climbing & dropping 800m over several bush covered knolls & rocky out crops before swinging NE & descending a bush covered spur (steep in places) & marked intermittently with permolat/ cruise tape, to the true right of the Ngaruroro River just below the forks with Harkness Stream. Once at the waters edge, head slightly up-stream of the forks with Harkness Stream & locate a good crossing point. One can either cross at the outflow or by swimming a deep slow pool near the forks. Once across on the other side head up-stream either on river terraces or in the Harkness riverbed to Ngaawapurua Hut which sits at the back of a grassy clearing overlooking the river.
Note: Described in the reverse direction to your journey
The route towards Otutu/Manson from Ngaawapurua Hut crosses private land and as such DOC no longer maintain it. To hammer the point home they have removed the swingbridge over the Ngaruroro too,.
From Ngaawpurua hut, head downriver either on terraces or in the Harkness riverbed to the forks. There is a good pool with the options to either ford at the outflow, or swim in the deep slow section at the forks. The river was waist deep when I visited in normal flows, could eisily become impassible, and even at in normal condiitions would not be recommended for those uncomfortable/unfamiliar with river crossings.
Once across, head up onto the terrace just downstream/opposite the forks - there remains of the track climb there, or just make your own way. A clearing exists on the terrace with potential for camping if the river were up, heading north. From the clearing the old track heads up the spur to the SW. The track is still marked with intermittent permolat / tape, but it not maintained. However, the ground-trial is fairly obvious - the track is moderately well used - and the spur itself is obvious. The route should not pose trouble to people used to following routes/badly maintained tracks.
Climbing through beech and later scrubby manuka you emerge onto a sharp rocky ridgeline, and 800m later reach the signposted track junction at pt1373. 1hr15-2hr30 hut to juncton