Hi NormK,
As I mentioned, these are just suggestions, I'm spitting out whatever comes to mind here lol. Please don't presume that I presume you don't know what you're doing, I know you know what you're doing
One test that may? if it's quantifiable? provide a result to my suggestion, is to have the engine bolted to one mower and rotate the blade disc to feel compression and resistance, then, move the same engine to the 600 and do the same test, see if there's a different feel to that compression/resistance from the disc?
