This article investigates the revision of technical texts on the basis of a project in which the revisers’ verbalizations were transcribed into think-aloud protocols. The analysis focuses on the operations performed by ten professional translators while revising an instruction manual translated from French into German. Raising the question of the tolerance of uncertainty in translation, the author examines the sequence of operations performed by the revisers to solve comprehension and expression problems which arose when the technical translator proposed several possible translation equivalents for a source technical term but left the choice to the non-specialist revisers. Based on their verbal manifestations of uncertainty, the results show that the revisers often stopped before acquiring sufficient terminological knowledge and that available information was sometimes not processed efficiently. The findings suggest that a lack of pre-existing terminological knowledge undermines the revisers’ overall certainty, preventing them from regarding the source text as an important source of knowledge acquisition and from establishing effective intratextual links.