We had a problem with the C-brake lash adjusters breaking on a N14. Every time it would break the top of the adjuster off, it would get wedged between the injector spring, and bend a pushrod. I latter found out that Cummins had a recall on that particular adjusting bolt so I changed them all with the updated one.
Even on the updated adjusters, adhere to the torque specs on the adjuster lock nut or they can break also if over torqued.