Snow Blowers

1830HV Snowthrower new October 2011. Used 1 hour last season. Worked fine, exactly as expected. Today when I tried to use it, the traction was intermittant for the first hour. Sometimes it worked, sometimes it didn't. After an hour, it worked normally. Linkage appears to be and function normally. No unusual sounds or smells, just unable to move under its own power reliably for the 1st hour of operation. On downhill grade, it would run away as though there was no engagement of the traction system.