Hi Jim and welcome to the forum. Breaking a chain link is highly unusual, not to mention several chains! As a basis for comparison, I have a few Drives and have been using them for almost 10 years -- never broke a chain link and never heard of anyone else breaking one either. Cable failures and swedge failures yes, but no links yet!
How much tension do you put on the chains? They shouldn't be taut -- You should be able to squeeze together the front chain/cable and idler about 1/8" and the rear cable about 3/16" at mid span.
Do you keep the chains lubed? Any indication of kinking or binding?
Are your chains lining up properly and squarely with the sprockets/drums?
What's the condition of the Drives -- are they operating smoothly? Are the drums reasonably snug or is there a lot of wobble or slack? Same with the idler sprockets. When did the problem start? Was it in conjunction with any other parts replacement or upgrade?
There are a couple of different chain/cable lengths. Are your replacements the correct versions? (should install with adequate but not excessive cable length).
Based on the number of broken chains on multiple Drives, it sounds most likely that there is a tension or alignment problem that is causing these breakages. If all else fails, maybe your dealer can help you sort it out?
