I have an early cat 236 skid steer and went to use it today and while I was running it I went to lower boom slowly and it would not go only if I pushed it all the way it dropped fast and was jerky then it clearing up was good for a while and. Did it again. When it happens it sounds like the motor changes sound and also like the hydro pump might be trying to do something else. All other motions work fine it was cold today like 30. Any help would be great