Joe - You're a better mechanic than you think. But not as good an explainer as you think. I'm sort of lost. I can't tell if you're trying to say your friend is moving the gear shifter and you're watching the cable move? Or, if your friend is pushing / pulling the cable somewhere under the hood, and you're watching it move where it is connected to the transmission.
Mostly it sounds like there's still a chance something has come loose under the floor console at the shifter.
In any event, this is all good news. Your transmission is still working fine ... if it were not, that would be much more expensive.
Keep mechanicing with your friend helping, what you're doing is making good progress. And saving MEEEEELLIONS.
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View my fuel log 2020 Mirage ES 1.2 manual: 42.4 mpg (US) ... 18.0 km/L ... 5.5 L/100 km ... 51.0 mpg (Imp)