Finding A Loco Address

[BobZ]

Is it possible to 'find' the address on a DCC loco when the owner doesn't recall it? I purchased a DCC unit from a private individual that was supposed to have been reset to address '3'. When I try to select '3' on my EZ Command it's not responding, both on the Mainline and/or Testtrack. This is a Spectrum unit.

Thanks