Perhaps this is a stupid question but very important, how do you prevent from the rubber to fall off when you draw chocolate? my chocolate is not too thick.
I use 150 ml syringes that I order from ebay.
If you don't do something like this already, try rubbing a little chocolate around the inside rim of the syringe before putting in the stopper/plunger part. This makes the stopper move easier.
I've had problems in the past with the rubber stopper coming off of the plunger, especially with older syringes, but this trick has solved the problem completely for me.