Check for flooded base first of all. tilt it backwards and if water runs out then you need to isolate the leak, if you can find it. After that then check for blocked hoses, particularly the clear plastic one that runs across the front of the pump, can be pulled off to clean.
if the base is flooded check which detergent the customer is using and have they just changed. also has somebody pre-soaked a dish with fairy liquid before putting it in. this happens loads of times.
however i find with these that the o-ring on the drain pump isn’t very good so i gently add a bit of silicone(not too much) to make a better seal. also i usually find that the lower arm support tower is not tight this allows water to slowly leak through into the base.
i also where possible re-install the machine with a slight lean backwards to keep the water level away from the over -flow. and have been known to block the overflow pipes, agreeing with the customer that a puddle on the floor is better than a soaked and blown spray pump.