Why do you think it is the balancer causing the vibration ?
Was it ever replaced before that you know of ?
The engine balancer needs to be balanced with the crankshaft assembly so replacing it could have the same result you have now -- a vibration
I have a good balancer with a repair sleeve included.
Shoot me an email with your zip code for a shipping quote. email@example.com
When was the tune brought up to spec with all new parts Last time ?
A good tune will be the very best thing to have the engine run smooth as is possible ( reduce vibration )
With that done you can look for the next possible solution
grab the fan blade and see if it moves front to back as your water pump bearing might be going bad
Condition of motor and trans mounts ?
engines will move around more in there seat if they are out of tune or a plug is fouling for example due to lack of maintenance which is 6,000 miles for our year cars
it is a very short interval compared to today car maintenance schedules