Over the past 3 years my team has had 3 mentors. Our first 2 didnt realize what it ook so they backed down after a year. When out last mentor resigned he took all his information and knowlege with him. He was not helpfull with making a smooth transition so as a result our 3rd year was more like our rookie year.
I would suggest talking with your current mentor and see if he is willing to help you make a smooth transition. Introducing you to contacts and helping you understand how things work will be crucial.