I have been making them suet cakes and they are on high protein crumbles. Maybe I should add some extra light.
17 months is right on time so rather than being broken, they're doing exactly as most breeds do - molt their second autumn and every one thereafter.
I say most breeds because I have a breed that molts their first autumn also, I also have an extreme cold hardy breed that molts in January.
Molt is rarely a naked bird - they lose feathers in a pattern by design so they don't have to be completely naked. Normally they just look scruffy and skinnier.
Suet cakes are probably too much fat.
Hopefully the high protein crumbles aren't a layer feed. Check the guaranteed analysis on the feed tag. It should be about 1% calcium. If it is about 4% that's too much.
It won't help to add light while they are molting because they still won't lay. Adding light simulates lengthening days which does stimulate lay. However, feathers are 90% protein, eggs contain about 6 grams of protein. It's difficult to make eggs and feathers at the same time. Furthermore, during the molt is an opportunity for hens reproductive tracts to take a rest and repair itself. Commercial operations have housed layers on a long day or sometimes an ahemeral day to get the maximum number of eggs. It isn't because they are concerned about the bird's welfare but to maximize profit- after all, in most cases they'll be slaughtering the birds in another 18 months.
I don't imagine that the majority of backyard people are planning to force lay till the birds are played out, cull and start with a new flock every 2 years. Some do though.
When first timers brag about how well their birds lay during the first year of production, I have a standard response: "~~A word of caution to new chicken owners with great laying pullets. Don't expect 300+ eggs after the second year. You'll be disappointed, no matter what breed you have."
Having chickens is usually beneficial for the birds and the owner. It should be fun and instructive. It's not hard and shouldn't be a time of constant worry. It helps immensely to learn about ones charge's characteristics, life cycle, nutrition, reproductive systems and metabolism. It's preferable to learn those things before one takes the plunge but at least shortly after starting the enterprise.
It's not just about the eggs - if it were, we would mimic the intensive cage systems that send $1.99 a doz. eggs to the stores.