Have you 'tuned' your bandsaw so that the blade stays in the right position? See below....
GET THE BEST TUNING FROM A BANDSAW 'Alex Snodgrass of Carter Industries has an excellent video
https://www.youtube.com/watch?v=wGbZqWac0jU on a tune up method that works well.
Tuning is only that and nothing else. If you really want to get the very best use of your bandsaw on an ongoing basis, then the Steve Maskery DVD's will show you far more and they are a real investment that you should own.
http://www.workshopessentials.com/shop/ '.
CHECKING BLADE TENSION - Flutter test Video's -
https://www.youtube.com/watch?v=chyo9chuwJs and
https://www.youtube.com/watch?v=z8zZuDosSy0
Whenever you have put a blade on a bandsaw, ask yourself the following questions:-
....... are you managing to get the blade running freely and central on the top wheel ( without guides or rear bearing near the blade ) with the gullet of the teeth in the centre of the top wheel ? The exception would be with wider blades, as 1/2" and wider may not sit 'centred' on the top wheel).
That's the first priority before closing in guides and thrust bearings. The blade will not be in the centre of the lower wheel as the manufacturer allows the top wheel to be adjusted and tilt to allow tuning.
Is the blade running vertical 90° to the table alignment, front and back as well as side to side?
Once the guides and bearings have been brought to the correct position, (not touching when the blade runs freely) is the blade remaining where it should be when run under power and switched on and off checking several times ?
Are you sure that the tension is correct, or as near as it can be. Each blade could be different, even if it is the same depth, so needs to be checked whenever changing blades.
If all these things are correct, then you should get a true cut unless you are trying to cut the wood too fast and it's filling the teeth with sawdust and pushing the blade out of line and see if teeth are damaged in any way.
Finally, if you have used the blade before, make sure the teeth are clean, as sawdust will stick in the teeth gullet. Cleaning with a wire brush will result in a far better cut before starting a new job, but certainly on a regular basis.
Malcolm