Quoted from northvibe:Who made the extended sparky protector? My pf was replaced and I forgot to swap it
Pinbits. Get the ones without the spider web engraved in it. Some have reported that the those break prematurely. Maybe the spider web engraving weakens it?

Source:
http://pinside.com/pinball/forum/topic/metallica-owners-thread/page/253#post-4236554