NH 1431 discbine repair help

Hi all - We could really use your help in figuring out what's wrong with our NH 1431 discbine. I'll also start by saying that we're not very knowledgeable or experienced with it, so please keep that in mind.

 

Something broke the last time that we used it. When it's on, the #3-6 modules from the left don't turn. But if you turn them by hand, those 4 will turn together. So - do you have any thoughts about what's broken and how we fix it?

 

Also, we didn't think ahead and took apart one of the modules before marking it for the timing (ugh). What's the easiest/best way to fix that?

 

Thanks for your help...

NH 1431 discbine repair help