Seeing as to how the P7 too is facing similar issues in rainy conditions (and in those two cases posted above, on milder gradients and in one case only a 19 coach load), it is puzzling as to how CR concluded that it is a problem with the locos. At least these two incidents definitely do not show any smooth operations. Particularly, in the second incident, the loco was an IGBT loco, which is supposed to have even better wheel slip control.
Also SCR operates 24 coach trains on the SC-KZJ section (which has a lot of frequent gradients) with WAP4 locos and as far as I know, they have never issued any such restriction. And in fact,...
more... in the same section, WAP7's have stalled multiple time because of wheel slip with the 22 coach LHB SBC Raj and the 24 coach ICF Telangana (AP) express, in rainy conditions. But both P4 and P7 continue to operate freely on this section.
It will be interesting to know how what forced BSL division to make this decision.