When I pull all the way back on the right stick to go backwards, the hydraulic temp alarm beeps, and says the hydraulic oil temp is high. Doesn't beep as long as I don't pull it all the way back. Is flow somehow restricted causing the oil to overheat, or is it just a sensor malfunctioning? As soon as I let the stick go back forward a little, the temp reads normal. Just can't back up full speed. Thanks.