Removal of a Stack member in a stacked Cisco swich unfortunately makes all corresponding information in the SNMP walk disappear completely, resulting in the related services becoming UNKNOWN. However, we need a service that will become CRIT in such cases.
This checkplugin for stackable Cisco switches keeps track of all Stack members upon Service discovery, issues CRIT upon missing stack members and WARN upon newly-added members. The members' individual switch states are also checked. After re-configuration of the switch stack, a fresh Service Discovery -> Tabula rasa is necessary.