First of all, consider disassembling the equipment and clean it thoroughly to remove any dirt articles. Take your time when cleaning the instrument as studies have shown that large dust particles can also damage the brass instruments.
Do not forget to oil the expandable valve box and consider inserting it into the dented valve. Use the palms of your hands to apply consistent pressure to push the dent out of the valve.
Apply oil on the fixed dent rod thoroughly. Take out the dented tube by clamping the vise to the table or your work desk. Use a dent ball at the end of the rod slowly and carefully to make sure the metal does not lose its shape. If you are unable to remove small dents in that area, consider moving the burnished slowly and quickly cover those areas. This can be done by following what you would do with a shoe brush over the face of the shoe.
Put in the dent rolling tool in the area heavily affected by the dents. Apply steady pressure to even out the dents. Do not push the metal too hard or you will break some parts of the instrument. Dents in long pieces of equipment can also be removed very easily. Inset the oiled dent ball slowly into the tube and consider applying pressure on the dented areas. Again, make sure you do not push the metal too strongly so it stays is in its original dimensions.