Tequipment is within their contract rights written on their policies when you buy from them, that is part of a sales agreement between the buyer and seller. After you buy something, no vendor or seller is obligated to serve as a warrantor of the products they sell; Amazon for example because its online, extends this to ~ 1mo; some credit cards like Amexco give you extended multimonth return-no-question ask warranties on purchases.
In the US, you are protected by consumer protection laws that are have different details in every state.
Before you proceed, you will have to read the warranty carefully to see if what you want applies to you and that you are likely right and they are wrong.
Send 1 certified snail mail letter with return receipt, addressed to a specific
named individual at the company such as the President or CEO of XXXX, America or USA, to insure he 'gets the message'. Imply intent to seek redress by legal means to show your purpose. Normally, such letters are written in lawyer letterhead to add more force to the letter. Use 10 pt courier font and use as few words as possible. Check the web for sample 'demand letters'. If your state has guidelines on writing demand letters, follow them for your particular state.
http://www.mass.gov/?pageID=ocaterminal&L=3&L0=Home&L1=Consumer&L2=Consumer+Legal+Resources&sid=Eoca&b=terminalcontent&f=30_day_demand_letter&csid=EocaGive them an ultimatum to reply by 10 days via email, or whatever is customary in your state; typically its 2 weeks, or 5 business days x 2 = 10 days, implied business days. Gently threaten them with also involving the BBB and the state Attorney General.
If you get no reply by the deadline, formally complain to the Better Business Bureau if they are a member, and the Attorney General of the state where the company is incorporated.
http://www.ohioattorneygeneral.gov/ConsumersAt the same time, gather the paperwork to file a small claim lawsuit or via mediation. Different states, different rules. Here's one.
http://courts.phila.gov/pdf/brochures/small-claims-court.pdfIn general, the threat of a lawsuit resolves the issue 99% of the time with companies of some repute, because a large company lawyer's time will cost more that the value of a small claims suit and most can't afford bad publicity, even if the company is in the right. BBB and complaints or suits go on their record, even if you haven't been able to collect, and this affects their chances from getting contracts with gov't or large companies, who will research their records for 'good faith dealings' with consumers and businesses.
Wait until you get a subpena to send them to show your intent incase your real intent is just a bluff. The cost to file a small claim suit varies by state, but its typically ~ $40-100; its generally a DIY lawsuit, no lawyer needed and its fairly easy to do, once you get used to it. Add to it the stamps and your time, determine if the effort is cost effective for you; for $1000 item, spending $100 to get $900 back may be worth it.