I just picked up a gently used Sportsman 400. I noticed the rear brakes squeak like they are staying a little engaged. How do i adjust that? Also i am need to do some maintenance, and i see there is a brake reservoir on the right side underneath the seat. I noticed, its completely empty. Im going to put some brake fluid in there. Is there anything i need to do afterwards? Also, do i add fluid to left brake lever on the handlebars, or does that get feed from the reservoir underneath the seat?