Could my engine be causing vibration?

[Duck Head]

Finished the build. While breaking in the motor I noticed that I had a tail wag. Took apart the tail and my thrust bearings had no grease in them at all. Greased them up put it all back together. Still has a wag with a small drift (nose left). Engine is broken in and it won't go away. When I run my fuel out of engine it gets way worse, so I am wondering if it may be something in the motor that could be causing this. I know that it is something mechanical because I put gyro/servo on my 600 and worked perfectly. Any ideas would be great. Thanks
OS 91 non pumped
JR 770 w/8900
Spektrum DX7
The tail drift is inconsistant also about every 5 seconds or so it kicks a little to the left, then wags then a little kick left.

[tholzing]

Had nearly the same problem with my 600. It took me some days to find out that the problem was the tail - a mechanical problem, which caused the gyro to make problems - on the tail torque you have the tail shaft - this shaft have to run very smoothly - if this is not the case - this may result in such problems.
I cleared everything with alcohol and used a little bit of sand paper for the shaft - after that everything was fine - no drifting anymore and also the "vibrations" gone.
All the best .....