New Engine w/ stripped clutch nut?

I wish I knew what this nut is called - but it's the one located directly beneath the clutch arm case. It's the one that needs to be turned when first installing the chain.

My problem, which I have never encountered in almost 50 kits is this: This nut is stripped and will not turn the small chain drive that I assumed is it's main purpose, aside from keeping it tight.

Although it's stripped, I pulled the spark plug and got the chain on anyway. I'm just wondering if it's simply not going to work - before I go through the trouble of completing my installation, rather than just sending it back.

Anyone have any thoughts or experience with this? I'd greatly appreciate it.

- Jon

I'm going to say it's called the "drive sprocket nut".

I'm not sure which is stripped, but I'd assume it's the shaft. The nut extends to the end of the threads, so I can neither tell which is stripped or really get it off. I could drill it or grind it off, but I'll probably either just run it how it is and test it thoroughly - or if there's any sign of trouble I'll send the whole thing back. Gotta love these kind of little surprises... I'll report back after trying it.