I'm running a dism /restorehealth cmd in Powershell run as an admin at the moment and it's running without error in lower case.
When a Windows update changed Command Prompt to Powershell in the Start menu, I changed it back so i normally just use the Command Prompt (Admin) from there.
You would only normally get an error 87 if you made a typo in the cmd line, so not sure why a correctly entered cmd should produce that error code until you capitalised dism.
Did the repair program run okay this time ?