What is the test for denying a motion to substitute counsel for abuse of counsel?

We review a denial of a defendant's motion to substitute counsel for abuse of discretion, examining four factors: (1) whether the defendant's motion for new counsel was timely; (2) whether the district court made an adequate inquiry; (3) whether the conflict between defendant and attorney "was so great that it resulted in a total lack of communication preventing an adequate defense"; and (4) "whether the defendant substantially and unjustifiably contributed to the breakdown in communication." United States v. John Doe No. 1, 272 F.3d 116, 122-23 (2d Cir. 2001) (internal citation and quotation marks omitted). "[I]f the reasons proffered are insubstantial and the defendant receives competent representation from counsel, a court's failure to inquire sufficiently or to inquire at all constitutes harmless error." Id. at 123.