Juanjo Forgot to mention I have a Wilfa grinder set to 2 for fine grinding.
OK as soon as I saw this I guessed the problem would be the grind…the Wilfa is a pour over grinder not an espresso grinder. I looked at the Videos, the shot against a blind filter generates just over 10 bar, proving there is absolutely nothing wrong with the machines
Rob1 Judging by the flow you need to grind finer, quite a lot finer really. Not to state the obvious but if the coffee can’t offer resistance the pressure won’t build up.
As Rob says, the problem is you need to grind finder, trouble is that grinder is really not suitable, and you need to purchase a better grinder (sorry). The minimum standard for a prosumer machine is really something like a Eureka Mignon. It will make all the difference. If you can stretch to something like a Solo/DF64, or a Niche, even better.
Get that grinder sorted and you won’t have any more problems.