What exactly are you hearing? Ive never heard of anyone having "bearing noise" with the balance shafts. Its much more common that the shafts are not times properly and are causing weird vibrations.

 

once the car is warm it sounds like a bearing rattle, ie rotational, present on idle, disappears under acceleration, coming from lower timing case, bonnet side. I tried with a stethoscope and thought I heard it also intermittently on the corresponding back of the balance shaft tunnel end. I'd love to find it was just a pulley! But it's just been through mechanics and had all the timing belt job checked. Maybe I'll get a second opinion.
Perhaps they've installed the BS belt wrong, they said it was over tightened and "fixed" it. Went to them initially because despite having receipts for timing belt just being changed, there was a ticking sound from timing case. Thing is I trust these guys, I work across the road in a parts store so they want me to recommend them.

Thanks for any advice.

 

there's a weird rattling sound when I revved my car up to 4500rpm. I've been here and there to have it check and they said its the balance shaft. did managed to fix it by aligning the top and bottom gear to the markings. but after I send my car for a head work(another mechanic) he said that the belt missed the gear by 3 so he fixed it and the weird rattling sound came back. does this mean the shaft is in bad shape? or maybe another problem