Siemens S25M230UK/01 dishwasher

Mmmmmm, a bit of a puzzle this one. I went to the original call, E15, and discovered a leak from the metering tank where it fits through the side of the tub. Fixed leak, removed water from base and tested. All seemed ok. I got a call to say it was doing it again a couple of days later. Of course I did the “What have I missed/done wrong” thing, and went back to find that all was good with my repair, but again there was water in the base. I removed the water and tried the appliance, having removed the side and lower front panels, and stared intently at it, from all sides, for the next hour, looking for a sign of a leak, but nothing was revealed. I explained this to the customer who was very understanding, and off I went with that nagging doubt feeling that we in this trade have become used to on occasion. A few days later, I got another call. It will only work on the quick 29 minute programme. On all others it gets so far through and then trips then RCD. I am going back to it tomorrow, and wondered if anyone else has had similar problems. Cheers. Steve.