rebuilding an 843 with isuzu engine. got machine together with new u-joint and a rebuilt hydrostatic pump. Can't get bucket hydraulics to work. I can raise bucket with machine running but only lower it with machine off and pedal in certain position and it will bleed down slowly. the tilt will tilt completely down but not up. I tool off the bucket position valve and took it apart. nothing looked out of sorts to me, cleaned it up and put it back on with same result. I think it may be this valve because the only function that doesn't go thru this valve is the up lift function and that works. I am considering bypassing this valve with some fittings to see if that is indeed the problem. Any ideas or experience ?