In this work, the behaviour of a palm fruit bunch press shaft is investigated, which has presented early failure several times, not reaching its expected lifetime. The study allows determining the failure mode of the shaft by using the finite element method (FEM). The model is used to estimate the load produced by the fruit bunches over the worm screw and transferred to the shaft. Geometrical analysis of the shaft shape helps to determine failure mode. The stress and strain fields are obtained to determine the critical points of the design, in order to propose modifications to the shaft design. Moreover, after a short time of operation, the structure presented plastic deformation, the hexagonal shape in the shaft is repaired using a welding procedure, as showed metallographic and hardness results obtained on surface and subsurface level of the affected area for the fractographic analysis. This is compared with a raw steel SAE AISI 4340 under tempered like original condition.