Usually manufacturers make a big deal if the VTA is adjustable. The best option is to have one you can adjust during play (rare). 20 degrees isn't the only cutter head angle. Some are 15, some are 17, some are in the range of 15-20. Your cantilever might also be off, so what works with one LP may not work with the replacement cartridge. After getting everything level, and lube, belt (if any of the former two) set, and the cartridge in the arm set-up with a protractor, you are set to fly. First thing is get the TT off any floor stand, get the dustcover off during play. Instead mount on the wall, or in a closet, and tough the disk, because in 98% of the cases the dustcover is attached in a flimsy way and it'll add to the vibrations. Analog is an art that is imperfectable - but can be very enjoyable, have fun.