Although I thought 10K was "permanent", recently a customer returned one that was completely worn off. The customer in question is a truck driver by trade (local route) so he uses his pen a LOT and he admits to being less than user friendly!!! The pen was about 6 months old.
The vendor that sold me the pen kit says that this happens a few times in a year and they were excellent about providing a replacement. I insisted to the customer that I would make him a replacement for free and it will be titanium so it CAN'T wear off. This all happened about 2 weeks ago. Today, he came in, picked up his replacement (TN for free) and ordered 7 more pens for the guys in his family-will order for the girls when he picks up and start on his wife's family thereafter.
ALL IS VERY WELL. But, the kit is $2. more in titanium and TO ME, IT IS WORTH IT!!!