Sounds like I should start with the cart and maybe wait a bit to buy an ‘investment’ phono stage.
Right, this one is perfect, but Americans don't know about it now, but earlier it was a Swiss made highly regarded phono stage, now it's cheaper, better, and made in Australia. One of my favorites, you can barely see it under the Gold Note PH-10 on my rack.
Re: springs, the TT is in almost perfect shape and is obviously a masterfully engineered machine. I personally wouldn’t try change anything about how it’s put together.
Those springs are the last things to try, and only if you want to play the game Miller playing for 40 years or so.