The same thing happened to me, until I started making sure not to tip it too far when flipping it over. so, just turn it over carefully into the vertical position and no further. Now it very rarely happens.
Agreed. I had a Classic for about 12 years before upgrading to an ECM Barista a couple of years ago, and I lost count of the number of times I had to strip down the solenoid valve to remove blockages. It's an annoyingly awkward procedure!