Pressure Washer - faulty (Gleadless S12)

Well, the sunshine persuaded me to get my pressure washer out today to clean my decking. However when I turned it on the motor started then stopped abruptly. I can't seem to get it to work, perhaps someone knows how to fix it? I bought it from B & Q a couple of years ago, I think it's one of their own brands, model number is FPHC100.

       
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