968: Rattle at 3200 RPM

Hi all, 

I recently purchased a 93' 968 with a great service history from a great PCA member. Upon receipt I had my specialist do some service/maintenance including a full belt service, motor mounts, radiator, some rollers etc. Running great BUT there is perturbing rattle/buzz which occurs seemingly consistently across gears at about 3200-4000 rpms. My first thought is a balance shaft issue as he was just working in there and had replaced the belt. Hoping to get this car as close to "perfect" as I can and am hoping for some help remedying this issue.

Thank you!