As long as its not an open or short, it should provide spark, but 200 is around where it should be.
If the spark box has failed, the spark wont come and go. It either works or doesnt, but wont be intermitent. Unfortunetly it cant be checked, the only way to eliminate the spark box is to swap in a known good one. Good used spark boxes go for around 15 bucks on ebay.
Most librarys have the service manuals, or you can buy them for around 20 bucks.

 

This had happend to me and my dad and i were looking and it was the Starter Silinoid (the spelling is probally off) look at this: HERE
Hope I could help any!