I purchased this machine a little over a year ago for farm use. I have noticed running the arms up while at the same time tipping the bucket back with and load will stop the arms from going up until I stop trying to move the bucket. Then the arms will start going up again. Almost like there is a one or the option. Is the control valve bypassing or am I not running the rpms high enough maybe? Haven't checked anything yet. Hasn't bothered me until today while I was moving snow around.
Nature of the beast, running higher rpms might make it less noticeable, or it will be faster and the stalling more noticeable. It's not one or the other, as much as the lighter load moves first. You can balance the loads by feathering the lighter load, so while lifting the boom you only open the bucket tilt slightly and they should both move.