To get down to the nuts and bolts of it means to get to the most essential part of it, but in this context the speaker is admitting that when the least essential part of it comes he is lazy.
Consider the staetement "When it comes to the least essential and unimportant part of it, I'm flat-out lazy.". Based on this statement, is "When it gets right down to the nuts and bolts of it, I'm flat-out lazy." a true statement? Yes/no/unknown