I have a La Pavoni Stradavari which is an Italian manual lever machine and it has a pressure gauge, custom handle, and bottomless portafilter. Manual machines are great because you can control how a shot is pulled and they’re easy to clean and maintain yourself.
I would recommend that you get a burr grinder and use fresh coffee beans (ideally local although honestly! I use Cameron’s Coffee organic espresso beans and I love them… very economical without compromising on quality). weigh out how much espresso you use in grams and play around with the amount and the grind size. I use 16 grams for a double shot with the beans I buy. Different beans extract differently and need more or less grounds per shot.
After grinding into your basket, break up clumps with a needle or whisk style stirrer, level it with a distributor tool, and tamp the grounds evenly. also make sure to regularly clean and descale your machine, and use filtered water if you have hard water with a lot of minerals (I love the BWT Penguin filter pitcher for the water I brew espresso with).
So get a new grinder and a scale if you need them and definitely clean and descale the machine, then follow the preparation steps I outlined if you don’t already and play around with one variable at a time. maybe log it in a diary and note any differences you observe so that you can know what made it better or worse! Looking at the puck after you pull the shot can give you clues, and so can the taste.