Ok, so this is what I learned in the Rotax course at Lockwood…. If after the oil purge the rocker arms have some give, run the engine for a period below 3500 rpm, as mentioned earlier. Repeat if still soft. What this tells me is that running the engine would push any air from the lifters, since the was no other remediation solution offered. But this would not negate the need to perform the initial purge. And I specifically asked about replacing the o-rings. The answer I got was that it’s not always necessary. So, I’d say depending upon the amount of time on the engine, it may not be necessary if you performed a long enough ground run and do a good job of checking for leaks after replacement. Anyway, that was my take away. I’m sure others on the forum took the same course and can weigh in from what they learned.