Since their mechanoids were designed with planned obsolescence so that they could always sell their newest models, mechanoid replacements would be sent out to mechanoid owners using the Diva-Droid Shuttles.
New mechanoids would be sent out in them to track their older counterparts. The shuttles were equipped with an on-board shotgun in order that the mechanoids might protect themselves from potential looters, or use them on any un-cooperative older models (the only time a mechanoid is programmed to be violent). The Diva-Droid Shuttles were intended to operate in the deepest of Deep Space, being hardy so that the new models would arrive intact, and could apparently last indefinitely.
Encounter with Red Dwarf
Hudzen-10 hunted after Kryten in such a shuttle for three million years, kept going only by his belief in Silicon Heaven. Given Hudzen's dialogue, he encountered the Felis sapiens in the surviving Cat Ark during his travels, since he knew of them (and believed the Cat to be a "viable target". Reaching the wreck of the Nova 5 sometime after Kryten had already been rescued by the boys from Red Dwarf, Hudzen tracked Red Dwarf by following the mail pods to Red Dwarf.
When Hudzen arrived on Red Dwarf, he was suffering computer senility, and found a non-dismantled Kryten and a crew willing to protect Kryten. Finally snapping, the upgraded model began to see them all as "viable targets", and began attacking them. They were only saved when Kryten convinced Hudzen that there was no Silicon Heaven, causing Hudzen to shut himself down in grief. Kryten did however believe in Silicon Heaven himself, but was lying, having been taught to lie by Dave Lister. ("The Last Day", Series III)