HI Quica
I had few issues like that with my printer at the start a few weeks ago and after searching the web high and low for answer I got chatting with a guy in the States on mIrc one night and his advice was to turn up the heat of the nozzle. Since then I am running the system at around 230 degrees and my prints are better for it.
Please note that this has worked for me and only a suggestion test with your own machine but let me know if it works for you.
Regards
Matthew