Gary -
I have never noticed the smell of mechanical parts or oil coming from a Whirlpool/Kenmore belt-drive washer unless something was not working properly.
Changing the belt may speed the machine up a little bit because a new belt won't bottom-out in the pulleys like a worn belt can, which slows them down. However, this won't affect the spin speed or the machine's acceleration time very much.
If this were my machine, I would check the pump to be sure it's not dragging down the belt. Other than that, I'd consider the motor being a weak link, especially if you already smell something like hot electrical parts. Motors are easy to change.
Gordon