When I curl the bucket all the way up to the end of travel the engine will stall,but when I curl the bucket all the way down the engine does not stall ,until maybe 3 or 4 seconds.when the bucket is in between up and down travel I can raise the bucket by hand several inches.If I cycle the bucket in and out a few times it will not do this.I have blew the cylinder and it will work ok for a while.I do not see any leaks anywhere.This is not normal is it?Thanks