By "not very well" WRT underground tracement, do you mean it has difficulty finding the desired circuit at all, or does it indicate an unduly wide, i.e., less accurate, or hit-or-miss area where it could be?
I do know a large percentage of successful locates- I presume above-ground as well- lies in the skill of the user (I'm talking about myself here). For example, this is undoubtedly true when a seasoned surveyor is using a Schonstedt ferrous metal detector for finding survey monuments, etc. versus a greenhorn...
