Learn Spanish (Latin America): A lo mejor la perilla se atascó porque giraste el dial. - Maybe the knob got stuck because you turned the dial.

Even though a lo mejor means maybe or perhaps, it is an exception to the usual rule where doubt triggers the subjunctive. It almost exclusively takes the indicative mood. That is why we use the indicative past tense se atascó instead of a subjunctive form.

Why do we use the pronominal se atascó instead of just atascó?

The base verb atascar means to block or to obstruct something else. By using the pronominal form atascarse, it translates to getting stuck or becoming blocked. The se shows that the knob underwent this change of state, rather than focusing on who or what intentionally blocked it.

Is there a specific difference between perilla and dial in this context?

Yes. A perilla refers to the physical knob that your fingers grab and twist. A dial refers to the face or mechanism with the settings, markings, or numbers that you are adjusting. Here, physically turning the perilla changes the setting on the dial.

Why are we using the preterite (se atascó, giraste) instead of the imperfect?

Both verbs represent completed, pinpointed events in the past. You turning the dial was a specific, finished action (giraste), which caused the knob to get stuck (se atascó) as a sudden, one-time event, rather than an ongoing description of how things used to be.