Don't let these people persuade you to tear the pieces out of your guitar!

Most likely, occasionally, you come across a cheap jack lead. Less expensive jack leads are made with less expensive components, the shaft on the jack, for instance, may be slightly shorter than spec, the phenolic insulator may be a bit thin, and the tip may be small(often, the cheaper ones are rounded rather than pointed), so that it doesn't make proper contact when it is plugged in to a professional spec plug (which your luthier undoubtably used when installing your bridge pickup).

What you need to do is to take your that jack lead that works at home and carry it with you. One of the things to remember is, you're only as good as the equipment you're using--that's why professionals cart so much stuff around.