Sunward SWT17S hydraulics problem

Hi all, A problematic Sunward has landed into my lap. Problem is in boom and bucket being very slow in movement unless track commands are being pulled or pushed. but only both at the same time. In that case, it seems like boom and bucked cylinders get inrush of oil flow and increase in speed of movement. Also left track seems to be slower than right one. I can see that boom, bucket and tracks share same valve block, but I can't find what the problem is. It is obviously in the parts that are common for these four elements, but I can't trace whele all the hoses go. I have tried looking for some documentation or manuals for Sunward, but so far, non existent. Doe anybody have any pointers? Ideally some documentation or hydraulic diagram? maybe not for this model, but at least something of same or similar construction? I have good general knowledge of hydraulics, but I lack in specific machinery and brands layouts and specifics. Many thanks in advance!!!