Here’s a link to a list of Teleflex "400" cables that will work great and are priced reasonable – several online places sell them – this one just happens to have nice list. They can be hard to find at some online companies without a model number. Teleflex does not have the cable ends:
http://www.boatersland.com/enginesystems-controlcables-tel400.html
Like RCO said, Marineengine.com is my go-to place for OEM parts. Inside the control box assembly, a bit of lube sometimes does wonders.
Dave