tefal steam generator ?

My iron switched off as it normally does when you need to top up the water but before I put the water in I held in the button yo start it up and it went bang and a lot of steam came out of the bottom of the iron. I thought it was broke but it has worked since but it keeps switching to the red light but when I switch it back on it has spewed a load of dirty water out it keeps doing it and I have cleaned it out there is something rattling around inside it and steam keeps escaping out of the bottom of the iron. I think it could be the valve rattling around.