Not sure whats different about yours than to mine apart from the soft arms(you apparently have,what are NOT available yet),but i'm still on the kit arms and also the same set of castor inserts that came in the kit and doesn't seem to have the problem your having
How often are you changing your castor setup during the day ?,because if your constantly changing them this will not help matters,as you remove them and insert them the area around the insert will of course get larger,theres not much that can be done with that i guess
You must make sure that the insert slots in straight and reasonably easy and not at an angle,as this will also enlarge the hole
How are you removing the insert ?,just making sure your pushing the pin from the opposite side and not trying to prise the insert out
Hope this helps
