Interior Lighting on K-line Heavyweights

I recall reading a post not too long ago about problems with the wiring on Kline Heavyweights: something about thin insulation and too little slack. I think. I also remember thinking to myself that I should save that topic/discussion, because I have a set of those cars. But I didn't. A search of the forum came up empty. Does anyone remember what the issues and fixes are, please? Two of my MR heavyweights short out the system. And that stops traffic on the Beer Line which is just unseemly.

Thanks very much in advance,

Jim