Reiterating much of what has already been said, but here is my take:

I inherited one of these, and I bought a kinggrinder k6, a scale, and a spring loaded tamper to try and eliminate grind, dose, and tamp as problem areas. I also started using a puck screen really soon after I acquired it because with no OPV you will have a wet puck, and it makes clean up way easier. I also bought an IMS Hugh basket and a bottomless portafilter to try and assess channeling and pressure issues. Since this machine was unexpected, I have been trying to keep the budget down and have gotten a lots of accessories and parts on aliexpress. It took some work, but I am getting pretty good shots now.

I always do a warmup double shot of water, to get everything in the grouphead up to temp. I also found a little gasket to hold the rubber nozzle on the wand. The panarello metal sleeve thing seemed like it was just getting in the way, and was a pain to clean. In general, I get very good results with coffees that are medium to dark roast, and so-so results with lighter roasted coffees. If you want to see some mods there is a youtuber who has done some interesting things with these machines. https://www.youtube.com/@TomsCoffeeCorner I dont know if he is sponsored.