Nutriscore was never meant and never advertised as an absolute measure of healthiness. It was always meant to be used to compare products in the same category. I agree that toast should not have an A but it doesn’t mean that it is healthy, only that it is healthier than bread with a worse rating. I agree that the values in the formula should be updated so that toast has a lower rating than whole wheat bread but that doesn’t mean the Nutriscore is useless.
That fan is not very standard though because it is a low profile 90mm. I only found a single replacement option thanks to a reddit post about this machine: Thermalright TL-9015W.