When changing any O-ring - work in steps:
- Remove the O-ring with a large needle. This will prevent damage to the aluminium part.
- Clean and grease the new O-ring and put it around the new dome (inside the groove).
- Then put the dome in place in the aluminium part and then start squeezing the O-ring in place.
- Squeeze the O-ring into the groove at a single place.
- Then squeeze the O-ring in the groove at the exact opposite side (180") of the first spot.
- Keep in mind to exactly divide the remaining part in 2 equal sections.
- Squeeze the O-ring into the groove at the exact center of each remaining section.
- And so on, and so on until the entire O-ring is squeezed in.