The biggest regular issue with 400A are the brakes and brake micro switches.The newer Mayr brakes are the answer to that problem but getting them will be hard for another company. All the other stuff about the SIMM cards is true. Cadi is not needed very often unless you wipe out a drive but access to the SMLCD is needed.
Newer software has a back door to give limited troubleshooting but earlier versions don't have that.