I found several different how-tos on fixing handrails on porches. I did not find anything that would tell you how to fix a solid one however. The only advice I found about solid handrails is that you should not install this type. It seems that those are nothing but trouble.
I would suggest that you may want to consider replacing it with another type.
You can get a lot of information on this at your local home improvement store. They should have instruction manuals on doing the job yourself, as we know it's really expensive to hire a contractor for these types of jobs.
I'm sorry I haven't been a lot of help to you, but sometimes replacing is better than trying to repair.