Go to the Brodak web site. I think it is www.brodak.com They are the largest control line supplier in the country right now. They have a number of planes including their Brodak basic trainer that would be suitable for getting restarted. On resetting the ball link that connects the piston to the connecting rod the engine will run without doing that but the durability will suffer. Ball link reset tools show up on ebay. My suggestion is that you fly a bit and decide if this is something you enjoy before investing in the reset tool.
Bob