I've just bought a Mavic Allroad Pro wheelset and I want to convert the rear hub from 12x142 to 10x135 configuration. I bought the 10x135 adapters (highlighted in red in the attached image, it's a section of Mavic manual) and I need to remove the original endcaps. I tried pulling them by hand but they don't move at all and I'm afraid of damaging something by using too much force. What is the correct procedure to remove the endcaps? Anyone knows? Couldn't find anything on Mavic site about this.