Start from the scope cable in counting house, the signal channel waveform should be linear (triangular). If a distorted waveform observed, check the input analog cables. Bad cable connection could cause such distortion.
After the two steps previous check, if problem is still existing, ask for an entry to open the door of lead shielding cave. Use scope to look at LEM output. In case of either high level offset or asymmetric waveform observed, determine to replace the module because that indicates the core part of H-bridge is defect.