Broken Cap bolt on Secondary

Here in California its been a low tide snow year, I have managed to make myself put 350 miles on my PC800. I have only had about 5 days of riding in snow over 2 feet deep. Here in Mammoth were in the midst of getting more snow in 2 days than we have gotten all winter. I have gone the 350 with none of the belt issues and only one lower A-arm,one fox float2,and 1 ski, all one accident (rock). So today I installed my new Powder pro skis, and was putting on my new 084 belt. But the while in the middle of tightening down the cap screw to compress the secondary, the bolt broke off inside the jack shaft. The bolt broke at the start of its threads. Now is where I need the help, I need the sled fixed today. My dealer is backed up, I need to fix it myself. I have basic knowledge on how to chase the broken bolt out, and the tools. But what caused this problem, I know how to take a damn belt off. Is this AC'S bad? Should I let my dealer do it for warranty purposes? Any input would be greatly appreciated.

Yea I used the washer, Im thinking there is a minor problem with the secondary. I just dont know what that problem is.

Fixed it! My dealer pulled the bolt off a sled he hasn't sold. Bummer for him not selling the sled, but great for me! I still would like to know why this happened.

Thanks for the advice fellas! I got it fixed the same day. Just in time for the 3&1/2 feet we got in 12 hours. I'm very pleased with the sled. Bottomless heavy pow and she ran 20 to 30 minute tree climb, boon dockin. With no issues at all. And it's still dumping, we doubled our total winter snow fall in 24 hours!