use a diesel cable
i had to replace the flex choke cable on my c27. i went to my local marine chandler and asked for a shut-off cable for a yanmar diesel. it's just the thing. if yours doesn't carry it, find a yanmar dealer and get it there. it's about 40 bucks and the only drawback is that it reads 'shut off' and not 'choke' - a small inconvenience at best.