first atv 1990 trail boss 250 2×4

wow! i was on facebook looking at a atv rally in minnesota. one of the guys told me to check out this forum. YALL GOT A TRAIL BOSS FORUM! totally blown away!

ive had my trail boss for a year now. its been fun messing around with. just rebuilt the carb on it. but i have a problem now i dont know what to do with. the "rear" break on the transmission isnt working at all. my friend and i took it apart and its not getting brake fluid at all. we bled the front brakes and those work perfectly. im kind of at a lost on what to do.

where can i get parts? whats a rear/transmission brake cost?
what kind of brake lines does this thing need?

did a little paint job on it. its just rhyno bed liner. hell of a lot better then the faded gray and red it use to be.