When do the optics in a gecco or venteon need to be cleaned?

There are cases where the optics of a gecco or venteon need to be cleaned. This is only necessary if the gecco or venteon

1. does not self start modelocking
2. has low output power
3. shows deviation to the spectrum shown in the certificate of conformity (e.g spectrum narrowing or broadening, cw breakthrough)
4. shows Q-switching

In such case please ensure to check the steps described in FAQ 'How do I measure the output power correctly?' and FAQ 'The output power and/or the spectrum do not match the data specified in the certificate of conformity - what can I do?' prior to any cleaning! Related to: gecco / venteon