Sorry, I haven't done any work on this type drive in about 10 years but as I recall the bearing was special, almost a proprietary design. But just for that reason Sumitomo was willing to share the information, because you could only source it from them.
I would suggest you contact your local Sumitomo office and see what information you might be able to obtain. Make sure you have the nameplate information available when you contact them.
The link below will yield the offices in the Philippines, your location according to your profile.