Thanks for the replies.
The engine has never left the ground under its own power, so far it has about a total of 2 x 16oz tanks of fuel through it, over 5 or 6 running times. Once only a full tank when I was getting the tuned pipe settings right. It was first started 2 weeks ago. I have read so many conflicting reports re the rear bearings, some have hundreds of flights and they're still good, others just a few flights. Ill look into getting a new bearing on monday. Apparently, from talking to other Aussies about it, a well stocked bearing supplies outlet should have stainless steel sealed bearings the correct size. Hopefully if we dont get a thunderstorm this afternoon /early evening Ill give it another go trying to lean out the low end.

BTW Im running 10% nitro, 15% coolpower homebrew fuel.