When performing a field balance job, many technicians will select a trial weight and then rush through the trial runs without paying attention to the readings they are taking. It is a good idea to look at both the amplitude and phase during each of the balancing runs. Upon taking the initial measurement take note of the phase and amplitude, in each trial run, you should observe a change in phase of at least 30ᵒ or 30% change in the amplitude of the plane in which the trial weight has been placed. If you do not get enough change in either phase or amplitude, then your trial weight is not large enough to get the proper reading. You must select a new trial weight and re-run the trial runs. This rule is also valid when performing a shop balance job with a soft bearing balancing machine since they also balance using the trial weight method of balancing.