I could be wrong, but I have never seen written confirmation of any
FEDERAL law requiring parts to be available for any specific amount of
time (if this does exist, I would welcome a link to it). Maybe you are
thinking of California state law (and similar laws in some other
states). Here is the citation for California:
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a) Every manufacturer making an express warranty with respect to an
electronic or appliance product described in subdivision (h), (i), (j),
or (k) of Section 9801 of the Business and Professions Code, with a
wholesale price to the retailer of not less than fifty dollars ($50) and
not more than ninety-nine dollars and ninety-nine cents ($99.99), shall
make available to service and repair facilities sufficient service
literature and functional parts to effect the repair of a product for at
least three years after the date a product model or type was
manufactured, regardless of whether the three-year period exceeds the
warranty period for the product. (b) Every manufacturer making an
express warranty with respect to an electronic or appliance product
described in subdivision (h), (i), (j), or (k) of Section 9801 of the
Business and Professions Code, with a wholesale price to the retailer of
one hundred dollars ($100) or more, shall make available to service and
repair facilities sufficient service literature and functional parts to
effect the repair of a product for at least seven years after the date a
product model or type was manufactured, regardless of whether the
seven-year period exceeds the warranty period for the product.
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Regardless of law, it's been my personal experience that unless you are
literally willing to take them to court, some makers will simply
stonewall you.