BMW Rocker-Arms !?
the M10 and M30 engines sometimes brake a rocker-arm. There are three types of rocker-arms BMW used throughout the years
BMW old on the left; second to the left the updated version from BMW; second on the right the febi replacement currently BMW OEM part; and finally on the right the after-market strengthened rocker-arm. As you can see for your-selfs the fist BMW rocker arm has considerably more material on the bottom eccentrics side (last picture). Of all the rocker-arms the updated BMW version is probably the weakest.
detailed measurement of the after-market rocker-arm febi including measuring the sliding pad geometry and modeling it in CAD and simulation by Finite Element Analysis software gives the following results at 200 Kg force on the tip of the pad:
new stainless steel valve
Old OEM BMW valve