that bit of a drag sound I would not worry about.....many make it, and many do not...
my opinion, if it ain't broke, don't fix it.....
it locks the tub and agitates, it releases and spins smoothly, and it stops on a dime as designed, I would leave it alone.....until something seriously happens...
I have one that 'knocks' 4 times when the spin is over.....and I have a spare to install once it finally stops working, but as long as it does what its supposed to....leaving well enough alone....
but if you insist, you might have better luck finding a whole tranny than the individual parts.....but still may take some searching