Hi! most people end up on the uk micro forum:
http://www.uk-micorc.co.uk.
Sounds like you've got servo centering issues.
This could be:
The steering assembly being over tightened, and binding.
The servo being of poor design/cheap and not actually centering properly
The servo saver not working properly, and not centering properly.
The first and last one are easy checks, and a Kimbrough servo saver can be fitted to a mini 8.
Hope this helps!
:-)