The little guy - Boiler cap O-ring
Boiler cap O-ring.
Please note: Do not overtighten the boiler cap, as this will potentially damage the O-ring.
Remove the boiler cap using the group handle as per the instructions. When tightening the boiler cap, the amount of force needed is equivalent to tightening the boiler cap by hand. If the unit is not hot, tightening by hand is more than adequate.
Rubbing a little cooking oil into the seal to help it slip is an excellent way to stop the seal from gripping the unit. This should help the seal last a lot longer.