How can I fix my Karcher Model K4.130?

Switched it on for the first time this year , and the water pressure from the hose connection to the Karcher is bleeding very heavily ,checked all connecting areas and seem to be ok ( externally ) looks to be inside the pressure washer where the leak in coming from, I do not have an allen key to fit to get inside and check , really annoying the fact you need special tools for something that may well be simple to sort.