I managed to reproduce the technique that I used the very first time I tried to brew a shot with Caravel. It was yet manual water heating those first days and I was so very concerned to preheat the machine properly etc. that - somehow pulled good shot, but didn't remember how
and then later couldn't just get any crema.
But no, it was not magic! I intuitively followed what was my idea of doing it the simplest yet proper way, probably accumulated from all the post I earlier read (and vids I watched - thanks Henry! - but the lever mounted not your way
). Also, I have no tamper nor anything that actually fits in the basket and could be used and that's a tricky point.
I preheat the cylinder letting hot water in and pressing the lever, then raise the lever and pull down again to press some more water through. Then I raise the lever to the point just before letting more water out and mount the pf with basket, then raise the lever for preinfusion and then press down. And always for pressing lever down I close the boiler and for raising it up and preinfusion - open it. If the boiler is open, there is air flow through the inside hole of the piston, upwards.
I made something similar to this routine on the very beginning and with the last shot. The inbetween shots, after I got the cord replaced were done without proper care for the preheating and without raising the lever before mounting the pf with basket, so probably there was some air in the cylinder.
Also, because of having no tamper and remembering how I got good shot tamping with my thumb, one time I thumbed with care LOL and another one (after seeing the result, which was no crema) didn't tamp at all (resulted in very thin crema). So today evening I got the golden point, the trick is to not to thumb too hard (OK - I'm going to sacrifice Schomer's Ergo Packer tromorrow with a help of an metal-worker
Anyway I'd like to stress the word managed that stands in the beginning of the post... after I started pressing on the lever, situation seemed really grave - I press, it stands, I get red, loose the force, it stands... I think I got hotter then the machine at one moment, pressing hard on the lever and on the boiler lid with my left hand - but finally something brown appeared at the bottom of the cup, and then - drop by drop - CREMA! It tasted differently then the way I remember first shot - less clear - but it was good! Like an essence of Vivaldi's double, but really it was tasty!