Disc unit having a small number of parts and capable of effecting fitting operation with ease. The inlet channel, the hollow pump chamber, and the outlet channel define a fluid flow path through the inlet channel, the hollow pump chamber, and the outlet channel. The performing of the installation process includes obtaining a content package, from over a network, which includes a manifest which describes a content type for each of the content items. Once inside the housing of the welding-type power source, the fan is positioned to generally occlude the opening and is then mounted to an inner surface of the front panel by a fastener secured through the front panel and into the fan.