Repair hinge on New World Sterling built-in oven door?

New World Sterling Model 016541
The left hand hinge on the oven door has become detached from whatever is hidden inside the casing, and can be pulled out a small distance. The door does not close properly when closed normally by lifting door, but can be pushed closed once it is vertical.
How best can I gain access to the inner part of the hinge to enable repair/replacement.