How can I fix my Technika ARDO Model SA1000 Front Loading Washing machine?

My machine operates correctly with no load (agitates, spins, etc) but as soon as I put even just a few clothes in it, the motor seems to struggle and doesn't have the power to agitate or spin the drum for more than a few degrees. It rotaes about 1/4 turn and just "humms". It is a reversing motor and the problem is the same whichever way it tries to rotate. I have replaced the PCB, but that made no difference. The machine is fairly new and the motor appears fine (no almondy smell or sign of overheating). Could the large capacitor be faulty and be preventing the motor from getting enough power? Thanks for reading my question and for any suggestions you may have.