The groove was as smooth as if it were machined in, and not so large that it interferred with the lifter operation. My only other option was to pull the cases and try to fill the groove with aluminum rod and gring it to spec. I elected to rebuild and ran it that way for 18,000 miles. I have since sold the bike with an aftermarket performance engine warranty. Thankfully, after new lifters, new camshafts and another top end rebuild the bike ran as well as before. I remember asking myself why those lifters were so inexpensive. They came as a package deal with the oil pump. When I spoke to the guys at Feuling, they gave me some dough to help with the rebuild, and the guy whom I spoke with said they were have lifters manufactured for them. I'm sure you are right about the change in operations. This was right about the time Jim Feuling had passed on. Good Luck with it. I just thought fore-warned is fore-armed!