I didn't have to turn a wrench, just a knob, to fix an issue.
My Rlaarlo MK-07 V2 1:7 trail runner/crawler stopped arming properly at start up. I'd turn on the Tx, then the vehicle, and I couldn't get throttle. The steering and everything else would work, but no throttle. If I then turned off the Tx without turning off the vehicle, I could sometimes get it to operate normally when I turned the Tx back on. I tried re-binding the electronics a few times. The attempts were successful according to the indicator lights on the Rx but the problem persisted. Curious... I was at a loss.
Someone from the Rlaarlo FaceBook group told me to check my throttle trim. Yup... turns out it was just a tiny hair off center, so the vehicle was sensing some throttle on start up and disabled the throttle channel for safety. A minute adjustment of the throttle trim got things back to normal. The amount it was off trim was pretty much unnoticeable by looking at the knob. I doubt I would have ever figured it out on my own.
Lesson learned!