Be consistent when writing

In technical writing, ignore the normal guidance about using synonyms to make your writing less repetitive.  If you mean the same thing, use the same word.

If you talk about a spade on one page and a shovel on the next, are you just being careless or do you actually mean different tools?

Any increased readability is not worth the added ambiguity.  This applies whether you are writing a technical report or a user manual.