I have blown up two pair of HE-6 by my own mistakes. Both were well out of warranty. The first pair was replaced at no cost, shipping included. The second pair was going to be sent free and I would not accept it unless I paid for them. I was charged $130 or less than 1/10th the cost of a new set. Each set I was instructed to keep the accessories (pads and fittings) and just return the headsets.
If you look at the pads, you can figure it out pretty easy. If the tabs are too flat, bend the tab out so that you can guide them under the groove. If you start the first tab with the pad angled slightly off axis, you can have three of the tabs in position a slight movement to proper alignment. Then it's doing what's shown in the diagram above, slightly bending the last tab under the groove.