For me, learning from my Cremina is like learning to be a parent.
Before our kids were born we read tons about how to properly parent children. We knew everything there was to know, in a theoretical sense, and we were not shy about giving others our parenting advice. Then our daughter arrived. Within a few months we greatly revised our thinking. Three years later our son arrived and now we don't give any parenting advice at all.
That attitude was also me before our Cremina. I had so many firm ideas. I liked my Silvia, and I was positive my Rocky grinder was ideal. When people would post about its grind variability I thought of that as its strength, smug in the belief that this variability allowed the full range of flavors to be drawn out. I was positive that exactly recreating the same tamping pressure time after time was really the key to great espresso.
Then I bought a Cremina. I bought a naked portafilter and somehow it took weeks to get things going right. I thought I was a pro at foaming milk on my Silvia, but this Cremina...
Must be the machine. I watched the OE rebuild videos and quickly knew everything to do. I dismantled my Cremina and immersed everything in a citric acid bath overnight. I then reassembled everything and it performed beautifully...for a while. Then water started leaking from the portafilter during warm up. I realized I had put both piston seals channel down, not top channel up and bottom seal channel down. Next I realized that the citric acid bath had caused some de-chroming on the brew head and yoke.
I wanted to have this baby right, so I posted requesting a business that does this work. No luck. Every place in my area does car bumpers, etc and had no interest in doing my pieces. I finally found a place 1500 miles away, took apart the Cremina and sent them my brew head and yoke. they said they'd get right on it.
2 weeks later I inquired and was told they had a 3 to 6 week backlog.
I now give no advice, I just try to take solid advice. This whole thing has humbled me in a really wonderful way, and I'm better for it, completely apart from the espresso.
p.s. I sold my Silvia and my Rocky, and bought a Mahlkonig K30 Vario. I was completely wrong about grinders, too.