The pins can jam, just knock them through with a hammer but use something a little thinner that the pins diameter. Common sence really.
The only danger with these brushes is if you dont remove them regularly to clean then they can seize in and also if put under pressure they will start to turn inside the brush centre which is plastic, once this happens they are very hard to get out and then you will find on replacement they will start to spin after a few uses. Its then time for new brushes and new pins.
Because of this they are a poor design......
When you do get themout safely, just clean and if you can clean the centre of the brush channel, but DONT grease,wd or put oil on them thinking it will act as a lubricant. If you do it will soon get black and will fire out all over the carpet when your using it.