problem with ext mics

I have a problem with the ext mic picking up the right side audio. I've done the 1/8 stereo (going into camera) to a two to one 1/4 mono(going to wireless receiver).This set up worked for me during a wedding filming and it sounded good.The very next weekend during another wedding it was only picking up the left side.To keep the weight of the cable off the 1/8 plug I tie the cable to the hand strap on the side to relieve the tension on the 1/8 plug hole.Anyone have any ideas? I've read other post about the same situation but no solutions

If exactly the same setup worked before, it must be that the the contacts in the 1/8" jack got bent a little. One good sideways tug could do it. I'd get a 90 degree angle adapter plug to prevent further damage. And it may have just enough of a different fit to make contact. The repair is expensive out of all proportion, because Canon service imposes something like a $250 flat fee to fix most things. If they replace a transport for that money, that's fine. But if all they do is bend back a contact it's a doggone shame.

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Fred