But nope. https://www.google.com/search?client=opera&hs=u1Y&ei=gq0hWqnELKmC0wLFi4uYCQ&q=Explorer+4250+HD+TV+box+%28Scientific+Atlanta%29+repair&oq=Explorer+4250+HD+TV+box+%28Scientific+Atlanta%29+repair&gs_l=psy-ab.3...2299.3679.0.4003.7.7.0.0.0.0.113.710.3j4.7.0....0...1c.1.64.psy-ab..0.6.593...33i22i29i30k1j33i160k1j33i21k1.0.vBQ8Jv_8OLQ

That long link suggests that repair and service is non-existent. That is, these are usually under contract from the cable co which will swap out dead units and then in their own depot repair centers deal with the dead units.