Chicken molting question

So my hens are molting...they were sold to me as hens at point of lay but they were underweight and did start laying a few months after I got them, they are small and didn't grow any after I got them, just put on weight. I have 10 they were laying great for a while then 5-6 eggs only, then 3-4, then 1-2 eggs a day...for weeks now. I checked vents tonight and 3 are clearly not laying at all, 3-4 are iffy, and 3 are clearly laying well. These hens are not even a year old (according to their hatch date from the seller) they shouldn't be having a hard molt at under 1 year should they?

I'm thinking about giving away the 3 not laying (with the disclosure of whats going on). But will the other 3-4 totally stop too? and the other 3 too? Are they not laying because of the molting? The other hens I've owned over the years never skipped a beat egg wise until the 3rd sometimes 4th year, as a group anyway, but I never had a hard molt either out of those hens.

Have I just been winning the chicken lottery for years and finally got a loser? Should I cull the 3, the 6-7 or all of them? I don't like feeding 10 hens in their prime egg laying time and getting 2 eggs a day, it stinks! Is an early molt worthy of cleaning house, or completely stopping lay during molt?

How long does a molt last.

I live in Michigan so my other huge fear is its not the molt its the change in the temp/light here and I won't get an egg all winter? I have a small light on a timer in case but no increase in eggs yet.

They don't have lice, worms, nutritional deficiency, or any clear illness. They are active and healthy looking some even look a little on the fat side.