In this work the structure of the tilted TGBC* phase is investigated by means of the line-shape analysis of Deuterium NMR spectra. The case of a rod-like mesogen containing a (S)-2-methylbutyl-(S)-lactate unit in the chiral chain, whose acronym is HZL 7/*, is taken. as a representative example for the large temperature range of stability of its tilted TGB* phases. By comparing the experimental and computed Deuterium NMR spectra. several structural features can be extracted. For instance, the analysis of Deuterium NMR line-shapes put in evidence the occurrence of helical deformations due to the effect of the external magnetic field.