Doc not fixing the starter makes no sense
We all know Doctor Emmett Brown to be a meticulous man. He recreates Hill Valley from scratch, and then apologizes for not being perfectionist enough to paint it or to build it to scale (I assume he means the proportions are not accurate in relation to everything).
Doc knows the reason why Marty hid the time machine; it was because there was a problem with the starter. How sloppily did Doc fix it, when the starter STILL doesn't function at all as it's supposed to? It malfunctions just as MArty is supposed to hit the pedal, it malfunctions again when Marty is trying to drive to save Doc.
How can this be? Doc KNOWS there's a problem with the starter, and he KNOWS how crucial it is to start the car at the 'calculated moment'! How can he forget or not bother fixing the starter?!
Sure, he might not know how to fix a 1984 or 1985 DeLorean starter, but surely those things can't be rocket science - which someone that invents a time machine should basically be able to do as well..?!
In any case, it makes NO sense, except from a Ryan George-sort of perspective, 'so that the movie can happen'..
I hate when movies inject nonsense, stupidity, implausibility, uncharacteristic behaviour or other things that make no sense just so that the movie can happen.