I got a few tiny cracks looked at on mine just before my warranty expired (European market),
and they offered to replace casing for free, or a new Mighty for €79.
If you are outside of warranty, what you might find is that they do not offer a repair service if the warranty does not apply, at least on their portables anyway.
I heard this on FC once and was skeptical but I have since confirmed it with S&B EU.
They may offer you a discount on a new unit, but depending on the price and terms they offer it might be worth it to check if the new one comes with a warranty or not,
as I just learned my new Mighty for €79 didn't come with the full warranty.
They consider it a replacement under the first warranty, which transfers over with no extensions to the period of cover, even though a (greatly reduced) fee and a new unit are involved.
So after two years we're on our own besides those discounts on new prices from the maker (and battery services from
@JCat ).
If anyone has a casing crack or something to get looked at, I would act on it at least one month before warranty end.
Then if you do get a reduced price new Mighty you'll have more than a week to figure out if it's as solid as it's supposed to be.