Snow Blowers

Bought a ST227P on 9/4/2015, I tested it the day I bought it and all worked fine. Yesterday I was getting it ready for the winter, checked the oil and again tested firing it up. The electric starter makes a quiet buzzing noise, but isn't starting the motor. The pull string starter fires up the engine with 1 or 2 pulls. Can you please advise what the problem and solution are.