Check the sliding slide for wear and adjust its tightness so that both sides are consistent.
Check whether the oil pipes of the two oil cylinders are connected in parallel, tighten the beneficial flow valve, pressurize and exhaust the air from the oil cylinder.
Generally, a one-way throttle valve is installed on the oil inlet (or return) of the two cylinders of the machine.
If the original work is synchronized but not synchronized now, try adjusting one of the throttle valves, which can generally meet the approximate synchronization of the two cylinders.
If the synchronization cannot be adjusted, there may be faults in two parts.
One possibility is that the throttle valve can not be adjusted to the oil flow you need, so you need to replace a single throttle valve;
Another possibility is that your speed is too slow, and the piston seal in the cylinder needs to be replaced.