So I got my DDM2 today and tried to delid some 775 CPUs. Two dead E8400 all good and delid fine. Dead Pentium D = knocked a sliver of metal up off the delidded edge and breaks the tool.
Exactly what happened was: I put in the CPU and lined it up, tightened the screw with the allen key, kept going as it seemed rather stiff, stopped to find the delidding edge had started cutting across the top layer of the CPU - damaging both the IHS and itself.
To get it to work now I need to make a shim of kitchen towel and put it under the CPU.
It seems that some of the older CPUs are shorter than the CPUs this is designed for. So watch out with trying random CPUs.
@der8auer