I have an older ariens 921 blower . Just had the belts changed and tuned. While blowing snow last night it worked perfect; this morning while doing some clean up it just stopped. I couldn't pull the start cord, it wouldn't budge; I wheeled it to the garage and hooked up the cord for the electric start, no go, it seemed the motor was seized up. I removed the pull cord assembly and put a rachet onto the big nut to the flywheel and pulled hard, finally it freed up and turned OK. I tried the electric start and it started and runs for about 5 seconds and stops; it sounds like it wants to go but stops. I let it set awhile and tried again; started right up ran 5 to 10 seconds and dies again. Any ideas? Please help my driveway is only 1/4 done! Just got 14 inches last night! Prior to the motor stopping it sounded like it was racing faster than usual and some backfiring last nite; it was also down 1/2 qt of oil.

The running initially and stopping after a little bit COMBINED with the tune up and low oil suggests an oil breather issue.
Replace the breather. Attached to crankcase with a hose to nowhere.