Petteroid governor problems?

[playdiesel]

Hello all,
I have a shot at a couple N.O.S. Petteroid air cooled singles, 6 and 8 HP. I had read some past posts about the runway problems but never did see anything posted on the exact cause or fixes? Also some models seem to be more afflicted than others. Anyone care to elaborate?

[TimSR2]

Runaways are fun to watch. You should bid!  (I've got a good detroit 4/71 story that goes along with that.)  Lol