Is there any sort or recall or cure for the failures of the balancer pulley's on the 320 engines?

THere are threeMB's in our office and two have had the balancer pulleys fail within the last week. (One made a real mess by failing while at 70 MPH on the highway, we looke at the other and it was coming apart the same way.)

Any info will be appreciated, I am now headed back out to the shop to remove the one we caught so it can be replaced.

Thanks