What is the reason why the forklift in Xiamen is not in place?

It may be that the gearbox is broken, the torque converter is short, or the two shafts (overrunning and clutch) slip, or the speed change valve is broken, and the gap between the walking pump and the suspension is large. It may be possible if all the above things have not changed for more than 1 year. By the way, it seems that the gearbox is short of oil and doesn't like to go, or the filter at the bottom of the gearbox oil is too dirty, so I thought for a while and quit for many years.