See comment below about screw under twistey knob under drainage tray. Think there's also screws in the rubber feet under the machine. Also, If you need to get into the inside where all the boilers are, 2 screws are on the back, top they are special torx head but you can get them open with a hex. There is a third once the back upper cover comes off that gives you access to the lower part of the housing. One of these plates is attached with an earth cable, just eave it attached. Once you get the upper back panel off you may want to remove the top, this just lifts out from memory.

Hello I had this problem, it was seals where pipes enter boiler. Service agent replaced them and all good now.