EX60 TRACK MOTOR QUITS ON ONE SIDE

HITACHE E60 Tracks work good when oil is cold but the right side slows then quits working after a few minutes. the left side keeps pulling. taking the right side track motor looks like big job. does this mean the seals are bad in the motor? Do I have to take the planetary gears off to take the motor off. where do i get parts for this motor?
any help would be great.

EX60 TRACK MOTOR QUITS ON ONE SIDE