Update 2. I thought I loved this machine. But, alas, just walk away. Better... Run.
I figured out the problem. The strainer at the base of the "portafilter" slowly gets clogged with unfortunately sized coffee bits getting jammed into the small holes - and cannot be easily cleaned. Rinsing cycle doesn't clean it. Cleaning cycle, with Krups own tablets doesn't clean it. You simply cannot remove the plate from the device for any sort of proper cleaning.
As the holes slowly start to plug up with coffee grounds, the pressure in the brew head builds up. Then pressure from the water shotting through the grounds starts pushing the plunger up. The more the plate clogs, the higher up the plunger gets pushed - until the first of the two gaskets finally rises above the seal mid-brew. Coffee sprays all over the inside, out the bottom, and sometimes a "Technical error" that will only clear after the inside of the machine dries.
If you ignore this warning, or already own this POS, here's the best I've found...
1. You can remove the stainless cover and "pill shoot" to get access to the brew head from the top. A stiff paint brush can clear some of the holes - alas this is how I now get my morning coffee most days.
2. You have to watch the brew cycle. If you see the top seal rising to the top of the brew chamber push "OK" to abort the cycle BEFORE the seal breaks loose. After the system clears, clean out some holes in the plate (using the brush) and try again.
3. Don't "abort" and walk away. The plunger is under pressure and will "seat" again after the water stops, this will cause coffee stuck in the brew head to flow back into the clean water system, a bacterial issue. You have to run 2 rinse cycles to clear the pipes.
I feel defrauded. This is a serious design issue.