What to do with a new Pelikan Souverän M600 with M nib that shows writing problems despite good ink flow?

The problem is mostly to be assigned to the nib itself, not to the fountain pen as a whole. At the specialist shop where the M600 was bought, the nib can be exchanged without complication; a return or complete exchange of the writing instrument is not necessary. The M600 is generally regarded as a recommendable writing instrument.