20 years ago I do not take a grid from the sink. What I do not remember is if they are covered inside or outside. I have a 4620 that had not worked for 10 years when I have it did not have oil in the back. I put shooting seals and pullout seals. I also checked the engine and put a new clutch. When I pulled the axis of the outbound, I could not see anything on the outdoor screen. As a fool, do not pull out the mesh but I started thinking that maybe the inside is full. The hydraulic system sizzles almost all the time. Is the interior that fills up?
The grid of the hydraulic crankcase collects the waste, if there are, on the outside of the grid. The plug that must be removed is on the left side of the transmission box between the hydraulic filter case and the rear axle trumpet. It has a square hole to accept a 1/2″ handle.
The check valve allows the oil to return to the transmission.