Sheryl, check with the Archives of Michigan for records. However, these would be covered under HIPPA laws so likely you would need a court order for access and copies. My grandmother was also a patient there and I tried to get her records also without success
There are twilight tours that you can look up and go on. One of them is acting led by the daughter of the former hospital director. I bet she'd have some insight on where to find things.
Try the main Munson hospital they may be able to steer you in the right direction
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