1. It never hurts to ask around -- call some other shops, explain the situation, and ask them for a ball-park repair estimate. Keep in mind that if you go the repair route, you'll likely be without a mower for several weeks as this is major delay season at mower repair places.

2. Based on what you've said about yourself, I would not attempt this repair. You don't have the experience, you probably don't have the patience, and you probably don't have the tools. Chances are the repair involves something like removing the engine from the deck, tearing into the deepest innards of the engine, putting in a new crankshaft, checking clearances, etc. IMO those kinds of projects are best left to people who do that kind of work for a living.

3. Depends on the value of the mower and the cost of a new one. If the repair costs more than the mower is worth, advertise it on Craigslist, mention the mower's condition, and say "for repair or for parts only." Somebody will buy it for $50. If the mower is worth more than the repair cost, then get it fixed (after which you can keep it or sell it).

Good luck.

The mower is only a year old. What did you pay for it? I would suggest it is probably worth fixing.

A complete new GCV160 is only $160-$240. Measure your output shaft dimensions and get a completely new engine.

Chalk it up to a bad experience ! Let it go to the highest bidder for parts. Don't Sweat the small ones ! You have better things to devote your time too !