The problem isn't with lead or lead substitutes per se, but as usual in their application.
Acids used in cleaning, fluxes used for adhering are the issue and cause the problem Mike experienced, I believe. The fact that it took 8 years to show up is puzzling.
As usualy improper application, cleaning, etc. of anything--lead or polyester, will lead to trouble down the road.
Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America