Brakes Locking Up--2003 Terex 860

Last Nov/Dec my rear Hydraulic brakes started locking up. I topped off the brake reservoir and the brakes were working fine. I didn't overfill it. Then it got real cold. Freezing cold. If I pushed down on the brake pedals, they would go down. By the third push the pedal would be right up on top. Brakes locked. Wait a few days, the pedal would go down again and lock up in the top position again. The brake pedal would not budge a pinch. I would leave it alone and in a few days, the...

Brakes Locking Up--2003 Terex 860

Brakes Locking Up--2003 Terex 860