Most of the vintage receivers used a diode mounted on a heatsink as a bias regulator to prevent thermal runaway. I've got a Marantz 4230 quad receiver. The bias regulator diode has a broken lead. It's listed as M8513 in the parts list with a reference designator of H718 & H719. They used to be available from from MCM but that was a long time ago. Anybody know where to find them?
