Hi all... I've tried searching for this problem - but I probably don't have the right terminology down... If there's a solution out there, please point me in that direction.
In the meantime I'll do my best to describe my symptoms (If it would help, I can even upload a video of the behavior).
My machine tends to work normally first thing after heating up in the AM. However, after sitting for an hour or longer after that first cup of the day, I get the following...
After loading the portafilter and locking in, I turn on the pump and the pressure ramps up to about 10-11 bar. Sometimes, not always, it will then drop to zero. Sometimes it will pump normally, sometimes it will hover around 10-11 bar but jerkily. Occasionally it will drop to zero and turning the pump on/off will not restart it...
After a shot is pulled and the lever is returned to the off position, the pump pressure gauge will go back up to 9-10 bar... no pumping is going on. If I move to the midway lever position the gauge will return to normal (atmospheric) pressure. Steam usually comes out of the head... or hot water will dribble out.
I brought the machine in to a repair place in Minneapolis, where I was staying for 6 weeks while on the move and the repair person said it was all fixed, he replaced the OPV and gaskets in the head. Nothing changed at all.. It exhibited exactly the same behavior.
He did mention that he saw signs of arcing on one of the electrical connections which he cleaned up.
Some other notes:
1. If I run an empty portafilter it flows water just fine, around 4 bar
2. If I run a blank portafilter to backflush, it runs about 10 bar, and will sit there all day
3. It's only when I'm pushing through coffee that it seems to act weird.
Any thoughts that would guide me?
Thanks in advance!