I have a ysm 12 and have rebuilt it, and my last thing to do is get the injector rebuilt. Problem is, the pre-combustion chamber won't come out of the head! Am waiting for any progress report from the machine shop, and so far no good news. Does anyone out there know where I could get my hands on a pre-combustion chamber or a complete injector? Reason I am asking is, if the only way to get it out is going to damage it..... I will need a good replacement part...... thanks!