Hi Pedrosa, I have two questions. The first is: what position are they stuck in, where the COV handles screwed in as for starting or out as for running? The reason I ask this is that it is a lot easier to free up a stuck plug by driving it in rather than trying to pull it out.
My second question is why do you want to pull them out? I think that the first run of your engine will probably free them, a mixture of heat and the shock wave from fuel detonating.
In my case the entire COV assembly has had to be replaced as the threads were damaged. I also made up a puller to remove the old plug, destroying it in the process.
DEV Precision, in India make new COV assemblies they would probably just sell you the plugs if you asked nicely. Alternatively ask your local machine shop to make you a pair, they are only made of mild steel and could be turned up on a lathe in ten minutes.
Bob