Charger only working on one side

Hi,

Got a Macbook 12" where the charging lead is only working when plugged in one way, and not when reversed.

A bit of history on this, I replaced the LCD/polariser panel on this, and the customer mentioned the issue when they received it back. This issue was not picked up during testing on our side, so it is strange the customer has noticed this.

Tested on an original Apple charger, and using the customer's Apple charger. I have a lot of experience with this model and others, so I know the basic precautions (replaced around 15 LCD panels for this model with no issues). Tried SMC/PRAM reset.

Haven't tried a new charging port yet, since these are quite difficult to come by, and we have not got another of this model in at the moment to try the part from.

Has anyone else experienced this issue? Could only find one other person online with this problem, and it was on an Apple forum, so there was no real information. Did not notice anything unusual when doing this repair either.

Thanks for the help.