I got my mantra and couldnt help myself, took it apart. My washers were luckily not dimpled like the OP's. However they are super thin. So thin that they were dished where the bearing balls run on them. So when i reassembled with a little fresh frog lube, I flipped them over creating a little spring. A couple of weeks later I opened it again mostly just to check it out, but also to clean and see if i could get it even quicker to flip ( it wasnt bad by any means). The washers were again cupped around the bearings. This time I used a little nano lube 10 wt and it might be a little quicker. On both reassemblys I was extremely careful not to over torque the pivot to avoid smashing the washers. I believe the washers are so thin that they are being reshaped by the balls like an english wheel shapes metal to make a fender. The OP's washers look like the dents are a little harsher on one side of the circle than on the other, probably from a heavy side load, not overtorquing IMHO. I wish i had a stack of phosphor bronze washers that were the exact thickness of the bearings, Im pretty sure this pivot would be just as quick and smooth with those and would resist grit better. Either way I really like this knife. It just seems that they tried to go too small with the bearing balls and too thin with the washers on the mantra. Sometimes the old way is better. Also be careful if you are thinking ceramic balls, they will wear on your metal parts much faster than metal balls with very minimal advantage in this application. Ceramic is much harder than metal, and not all of the forces are rolling forces, there is some twisting and sliding done in there also( very small amounts). Done , thanks.