The most significant scoring dings, and thus the most room for score immprovments, comes from reporting payment history derogs.
Major derogs place the consumer in a less favorable category ("bucket"), and significant score jumps are usually not seen until payment history is cleared of the last major derog.
With a collection and a charge-off, large increases upwards of 50 points are not likely until both are excluded or deleted.
Tweaking % util is good, but not likely to produce the level of score increase posed.
