Since the (apparently) older route that ascends the nose of the ridge below Sellers Potrero isn't given mention here, I'll start with that description & then move on to the Sellers Potrero Trail proper.
Section- Wilderness boundary to Sellers Potrero Trail- This route, apparently an abandoned jeep road, alternates between open &very brushy, but is never very hard to follow. A few downed trees complicate progress, but the tread is always easily discernible.
Section- Sellers Potrero Trail from Wilderness boundary to junction of (historic?) trail described above- Trails is generally in excellent condition, with some encroaching vegetation & a bit of deadfall. Minimal restoration needed, but all could likely be accomplished with loppers & a small hand saw.
Section- aforementioned junction to Balm of Gilead Camp- Trail is generally in good condition, but 3 downed oaks force detours. As I recall, all are large enough to necessitate crosscut saws for removal. Some brushing would be helpful here & there as well. Once in the canyon, poison oak abounds; Balm of Gilead Camp was basically bone dry, save for a tiny puddle of standing water (& this was just after a heavy rain). Campfire ring needs hazard reduction to clear vegetation & dry grass, camp toilet is completely defunct & somewhat dangerous as the platform looks rotted & could collapse under weight, recommend filling it in, decommissioning, burning wood & packing out the seat/hardware.