Okay. Other than the condensate drain, and the water fliter system, the only other possibility is the water cooling tank. These are not under pressure unless the dispenser is pressed for some cold water.
Access the back of the refrigerator section and remove the panel covering the water holding tank. Dry it off completely with some paper toewls or newsprint.
While observing the tank for leaks have someone operate the water dispenser continiously for at least a minuet or if no leak is apparent even more to be sure. You can put a finger partially over the dispenser nozzle to add more pressure to the system for a more vigirous test.
Some units use a coil of hose instead of a tank. Just be sure to dry inbetween as many of the coils as you can before starting the test.
Keep a close eye out for water coming from above as the filter may be the problem.
Please let me know if you need anything else right now.
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