Your leasing contract with Xerox, (or any other capital leasing, funding entity for that matter) is seldom ever intermingled with a service contract. In many cases, the leasing company isn't even affiliated with the manufacturer. They are in the business of leasing equipment and making a profit on the interest. In this case, Xerox just happens to "hold their own paper" when it comes to their equipment leases instead of letting that income go to a leasing company. It may be confusing sometimes, because, Xerox may invoice you for your lease payment, and, the service contract on the same invoice, but, if you read the two agreements, each has absolutely nothing to do with the other.
For a lot of high ticket items in print and mail shops (folders, inserters, presses, etc) a business owner may elect to lease instead of purchase for various reasons. In many of those instances, the leasing company is a separate entity that the equipment manufacturer uses in the normal course of their business. Sometimes, the original leasing company may even "discount" (sell) your lease to a totally different agency. If your equipment ceases to function properly, the lease holder is under no obligation to reimburse you for the time you were deprived from the use of that equipment.
Do not think that you are the ONLY injured party when your equipment is down. You are not in this alone. Xerox is also being deprived of the income from clicks off of a machine that is not running, and, they will want to get it up and generating revenue as quickly as possible.