Weve broke the chain once per year on the Dragoe 12-30 we have.    First year we had shear bolts breaking once every 300 acres.    Second year we throttled down when engaging the header, broke one bolt this year.

 As far as the chain, I dunno, Are ya checking the tension every other day?   That seemed to help us a bit.    FWIW:  that chain issue shouldn't happen, but it does, and the drago guys reading this need to engineer something to fix it.

 Good luck