Zanussi FJ 1295 blows Earth leakage breaker on the house

I hope one of the experts can help here. My Zanussi FJ 1295 trips the main old style 60amp ELCB in our 1960’s house. None of the fuses blow after we reset the breaker. The fault appears to happen on any program setting – although we’ve only tried a D and a G settings as it got dark (and dark house and children don’t mix well). I’m guessing, being an ex-electronics engineer, that there’s an imbalance somwhere that’s tripping the breaker and not a high curret being drawn – although I could be wrong. Before I start looking inside tomorrow for any clues, does anyone have any hints on areas I should look into. I should note that the main drum motor has had new brushes professionally fitted about 6 months ago, I’ve flushed the exhaust pump of chalk and grime a couple of times in the machines lifetime, but otherwise there’s been no pre-emptive signs of this new major event. All and any help gratefully received. -Andy