I have a experience with intermittent failure of the brakes. When driving in cold environment the oil around brake disks gets so thick that it can not drain away from the brake piston (the piston that presses on the friction discs). It builds up a thick film of oil. After the machine has been idle for approximately 30 sec, you can press the pedal to the floor because now the oil has sunk down and the brake piston gets a longer stroke. When you have pumped the pedal one or two times the brakes seems to be ok until the next time With Cold enviroment in combination with ideling for 30 sec or more.
The soloution for this problem was new brake pistons with draining slots and a thinner oil.