If you don't use the system properly and use freshly roasted beans without using the vent in the brew chamber cap, leaking or bursting can occur due to CO2 off-gassing.
Freshly roasted beans release CO2 gas and when the CO2 gas expands it can cause leaking from the base or in extreme cases bursting. This happens because that is the only place for the gas to go and escape the otherwise airtight chamber.
This is totally preventable by using the system as instructed. Simply remove the Extract Chamber while brewing and instead screw on the Brew Chamber Easy Pour Twist Cap (for venting) and turn it to the open position so any CO2 gases can be released, and letting the coffee breathe. See page 24 of the users guide which illustrates using the brew chamber cap and leaving it open so the coffee can breathe.