grammatical person - How to avoid mixing past and present tense in narration?

I looked through the related questions, but I didn't find any concrete advice.

I understand that it's OK to do so. I'm not sure how common it is, but I'm a beginner writer and want to keep things as simple as possible. I can pick up that fancy stuff later.

To illustrate the problem, I'll use the following example, where first-person POV narration has present tense sandwiched between past tens in a single paragraph.

I wound through the corridors toward the center of Down 15. None of the elevators were nearby, so I bounded up the stairs three at a time. Stairwells in the core are just like stairwells on Earth—short little twenty-one-centimeter-high steps. It makes the tourists more comfortable. In areas that don’t get tourists, stairs are each a half meter high. That’s lunar gravity for you. Anyway, I hopped up the tourist stairs until I reached ground level. Walking up fifteen floors of stairwell probably sounds horrible, but it’s not that big a deal here. I wasn’t even winded.

From "Artemis" by Andy Weir

When I go through my texts, I see that I'm doing the same. I'm writing in first-person POV, past tense, but when it comes to descriptions (little info dumps) and the narrator's thoughts (comments) I often switch to present tense (without thinking).

The problem lies in the word "often". I don't do it consistently.
Also when I find a spot like that I start to think can I really do that? If in the above example the Moon was blown up by the end of the story, would it still make sense to talk about the stairwells in the present tense? It's just too complicated to deal with all these logical traps. I want to keep it simple.

I can't just search for present tense (such as "are") in the word processor. As we use the present tense in the dialogues.

Is a good copy editor the only option?

Or is there maybe some mind trick that one can use? Like maybe one needs to pretend and always keep in mind that a story is told by a person who is at his/her death bed, the events happened years ago, and the storyteller doesn't know anything about current state of affairs (what happened to all these people and places). Can a certain mindset break a habit?

Any other ideas?

Please advice.

Answer

How to avoid it?

By Being Meticulous. There is no shortcut. You, as the author, are responsible for every word choice in your story. Every single one.

It reads fine to me to have the present tense as presented in Weir's snippet, but it could be clearer.

In first person (past tense), a thought can either be italicized and immediate (in which case it becomes present tense) or not (and remains past tense.)

You are the God of this world you have written, and you are responsible to know every detail of your creation. So go through it. Sentence by sentence. Figure out which thoughts of your creation are passing surface thoughts, and which are intimate deep thoughts.

If that passage was mine, (which it isn't; I have a different world), I'd do it like this:

I wound through the corridors toward the center of Down 15. None of
the elevators were nearby, so I bounded up the stairs three at a time.
The stairwells in the core were just like stairwells on Earth—short

little twenty-one-centimeter-high steps. It made the tourists more
comfortable. In the areas that didn’t get tourists, stairs were each a half
meter high.

That’s lunar gravity for you, I thought.

Anyway, I hopped up the tourist stairs until I reached ground level.
Walking up fifteen floors of stairwell probably sounds horrible, but
it’s not that big a deal here. I wasn’t even winded.

Do you feel the movement into the character brain? You have this tool available to you. Don't overdo it--develop a feel for when you want a direct thought from a character. But you need to be obsessive about going through your story with a fine tooth comb and making conscious choices. There are multiple ways to write any passage.