Hello mate,
I had this problem with my sons zip, you can get a bleed kit from M & P in Coventry, its called a 'little bleeder', it stops the fluid returning back through the pipes. Otherwise you will be there all day. Cost ya about a tenner and you should be able to get one from a bike shop near to you.
I would just fill the res up with fluid and use one of those.
Paula
June 2008