Changing a single GP4300 cell

[DaveG28]

Hi all,

have sold a few GP4300 packs of batteries, and unfortunately there seems to be a dead cell in one of them, and the buyer has asked if I can replace that cell.

However, as I've already accidently screwed him round once (I hadn't had a problem with the pack so stupidly didn't check the cells before sending!) don't want to do it again by getting a replacement cell and then finding it is a bad thing to add that to a matched set etc.

Would it be better for the guy if I refund the price and then junk the pack, or is changing a single cell viable?