Family Search now has probate records (various years) for 67 of Michigan's counties. Kalamazoo and several of the surrounding counties are included.
For Kalamazoo you'll find:
probate calendar index, 1833-1940
probate calendar, 1875-1907
probate of wills, 1856-1916
probates index, 1833-1889
settlement of accounts, 1887-1907
While you won't find probate packets here, there are several indexes so this is a great starting point.