1. Put a piece of ා 600 sandpaper in ATF oil and soak for about 30 minutes. Carefully tap the valve body to remove the stuck stem from the bore. It may be necessary to lever it out with a small screwdriver.
2. When using the screw driver, be careful not to scratch the valve hole. Check for friction marks on the one-way stem. Grind the burrs on the valve stem with ා 600 sandpaper soaked in ATF oil, then clean the valve stem with solvent and dry it with compressed air.
3. Roll up half of the ා 600 sandpaper soaked in ATF oil and insert it into the valve hole of the stuck valve stem. Gently loosen the sandpaper and stick it tightly on the surface of the valve hole, and then screw the sandpaper to grind the valve hole while pushing and pulling. Pull out 600 sandpaper.
4. Clean the whole valve body with solvent and then dry it with compressed air. Coat the surface of the valve stem with ATF oil and drip it into the valve bore. The valve stem shall be able to fall into the bottom of the valve bore with its own weight. Otherwise, repeat step 4 and retest. If the stem is still stuck, replace the valve body.
5. Take out the valve rod of small concrete mixer and clean the valve stem and valve body with solvent. Dry all parts with compressed air and reassemble with ATF oil as lubricant.
6. It is suggested to clean the concrete storage tank and the surrounding of the inlet and outlet to ensure that the concrete does not agglomerate.