Few thoughts as a buyer:
1. We purchase from a OEM dealer because we don't want to get an auction what ever is happening 4 possible wheeled vehicle from a smaller independent dealer. So, we pay more for peace of mind. My other choice is rolling the dice with a rando or FB add. We have bought into that 150 point check points that we get told about.
2. If the vehicle was sold knowing it has a problem, I would rather loose a sale by telling the buyer up front. I've heard and read here a few times about long distance shipping and pointing an issue. Point it out ... better yet, sell it auction or fix it before selling. My buddy who ran an independent and lived on auction duds, would rather eat a bad purchase than sell it with problems because the customer knowing 1000000% that it's broke, will still bitch to everyone that he got screwed.
3. That $4200 is a tough one. I would maybe negotiate it away. Maybe, free labor and half the parts. But ...another thought is that a small town is poisonous. IF someone in the dealer is related to the person who bought the vehicle talks about how y'all sold a lemon and denied it ... game over. That $200 gets a force multiplier and a good solid 5-10 year reputation. On the other hand, if you cover it and law down rules to follow and every one gets a firm warning, but nobody gets the blame, the rumor will spread that you're fair and did the right thing by the customer.
TLDR;
Eat the $4200 this time and law down the law on how things must work.
I talked about scrum calls last time.
Here's something that most people don't consider when using a Kanban board. When you move a ticket across the board, it must have entry and exit requirements.
You really need several kanban boards setup through out the dealership. Every process needs to be documented and then later you can audit and adjust.
My dev team before they get their work reviewed by a peer must show the person who wrote up the task to confirm the over all task was accomplished or not according to the criteria of the task.
An example of exit and entry criteria:
paint a car
The color is checked by the customer before it goes to the paint quality inspector. What use is it to check the paint job if the customer was expecting a different color. lol, we deal with "buttons" like this "post reply" a lot.