There are no user replaceable spare parts for Inon. They replace the entire internal strobe assembly as a whole. Which is why I've always said Inons are the plastic throwaway strobes.
I almost feel like putting down legal disclaimers when people ask for advice like this. But I'll just add this:
WARNING: if you have had batteries and turned on the strobe, realize that the capacitors still hold a charge and can shock you if you touch the wrong thing. Wait at least a few hours before opening up the strobe.
Curious, does this mean that the "spotting light" would not be replacable? I have had one out for quite awhile and have thought of trying to replace it.