The cost of replacement used to be much lower than the $279 cited in the first post, and it occurred to me that nobody here has questioned that detail.
I just called URC and was told that I, as a dealer, can get a new MX850 as a replacement for much less than was originally claimed. The warranty on this replacement unit is one year.
A good answer is easier with a clear question giving the make and model of everything. "The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw