MarineEngine.com does not offer troubleshooting assistance or repair advice by email or by telephone.
You are invited to join our public Boat Repair Forum to seek assistance from other members.
You may also visit the Boat Motor Manuals section of our site to obtain a service manual.
8M - 8 horsepower Manual (rope) start from factory
677 - model number - equates to (mechanically) an 1977 Model 8B Yamaha (which Yamaha sold under their own brand)
S - short shaft (for 15" transom)
056729 - actual serial number - 1983 "production" so would have been sold as a 1983 model "Mariner" but was "mechanically" a 1977 Yamaha.