E61 group valves
Inside the E61 group
Rocket's manual says not to attempt repairs yourself: contact an authorised, qualified technician, and any repair must be done by Rocket or an authorised dealer using only original parts. Rocket does not cover damage from unauthorised changes or non-original parts. Treat this as dealer work.
Clive Coffee's description of an E61 group, not Rocket's: an upper valve under the top cap, a brew valve in the middle and a lower drain valve in the bottom piece, whose spring pushes hard as it comes undone. Clive rebuilds them every 3 to 5 years with a kit, using two wrenches and a cloth between wrench and chrome. The FAST sheet also lists a 0.7 mm gicleur (A229908604) and its filter under the cap.
The FAST's group has a heater and probe that other E61s do not, and Rocket's group parts for it are new numbers (R019908…). Leave this to a dealer.