I have a 856 A  too, I think they are great baler, I will take the couple exta chains any day....  Drove a new JD for a day last summer , not impressed, gets old yanking on the hy lever every bale. my only agco complaint are the pickup teeth,  I put a few JD square teeth in for cornstocks, now I need to figure out how to put two little bends in the JD teeth with out taking the temper out....the net wrap sys is bullet proof and belts will always be belts.
My first baler was a 560a so  that was a learning curve for wiring, magnets,and elec/hyd.......