This paper presents the performance of a commercial lead quality monitoring library (LQMLib, Schiller AG) for detection of reversals between 12-lead ECG cables with matching colors and proposes methods for improvements, where necessary. The study is performed on a large 12-lead ECG database with 1331 chest pain patients (646 training, 685 test recordings) and ECGs from 29 volunteers with swapped red, yellow, green, black and all unicolor cables. Relying on assessment of inter-lead correlations over continuous 4s episodes, LQMLib without adjustments achieves Se>97% for all unicolor cable reversals, except RC1 (Se=29%) and NC5 (Se=88%). The proposed additional analyses improve RC1 and NC5 swap detection by 63% points and 7% points, respectively.