The difference is amazing! You started with 125 grit?
I did...started with 125 Grit on my little weak B&D Mouse sander...light & quick sanded just until it was smooth to the touch. Didn't take much at all.
Then using my sanding block, 600 Grit, with 600 grit again with my hand to hit any spots the block couldn't get to.
Then 1000 Grit by hand (no block), then 2000 Grit (no block) to get everything to a slight shine...
Then Meguire's OneStep Compound (has a slight fine grit) by hand to get the spots the buffer can't, then with the buffer...
Then Meguire's Polish with the buffer, then a 2nd coat by hand.
My cheap little Harbor Freight buffer smells like the motor is burning up after about 2 mins of work...hoping it makes it through!