(3) The pressure in the reverse gear and the second gear is normal, but the pressure in the first gear is low. This is because the seal ring at the junction of the first gear clutch assembly and the transmission body are damaged, or the piston seal (piston ring) in the first gear clutch of the transmission is damaged. Check whether the oil seal at the connection between the first gear clutch and the housing is damaged. And remove the 1st gear clutch cylinder, and replace the sealing ring if necessary.