T have a kobelco sk200lc it's got a new pump and engine. The crowd cylinder will go out great as a matter of fact probably too fast. When it's returned it will get to the point of balance and stop when the hydraulic fluid catches up it will start to move and come on in. I have replaced the hoses and cleaned the filter in the shuttle valve assembly and the relief valve for that function. So what have i missed?
There is a port relief for both directions you could swap them and see if it changes. also the arm circuit has a regen valve to speed the function up. You could also try swapping pilot lines to make sure it's not a pilot issue
Are you checking this with the engine at low rpm? ....at idle? If so, check it with the engine at full throttle. Does the crowd cylinder drift at all?
Good day If you operate many excavators digging fresh air most will suffer the same fate, put the bucket against an obstruction will be a different outcome. Kind regards Uffex