Oven won't light.
Localwonder gave a more comprehensive answer, but I wanted to share my recent related experience too:
Same model: MGR5750BDW
Oven was not heating up, or would sometimes and not others. Broiler worked fine. The nice thing is that the broiler igniter and the oven igniter are the same part. So I swapped them until I could get a replacement part.
Before I did anything, I turned off the gas!
To take out the broiler igniter: there's one screw right near the front of the oven that holds the burner assembly in place. Remove that, gently pull the assembly off the gas nozzle off to the left. Then where the wires from the igniter go into the back wall, remove the screw that holds the little door, remove that little door, and then gently pull the wires through until the connector comes through the opening. I also found you can go behind the stove, remove the back panel (which is easy) and see the igniter's connector.
The oven one: remove the floor of the oven by lifting it at the back, and then lift it out towards the back of the oven. Then you can see the igniter at the back of the floor of the oven. remove the two mounting screws, and then gently pull the wires until the connector comes through the insulation.
The bad igniter looked like it had burned down to bare metal in a big patch...not sure if that's the actual problem, but in any event, I installed the good igniter in the bottom (gently pushing the reconnected connector through the insulation, and feeding as much of the wires down in there as well), and the bad igniter in the broiler position (since that was the easiest one to access and replace, it'll be easy enough to replace when I get the parts). Tested, and everything worked great. And I could watch the bad igniter light up, and never light, confirming that it was the igniter itself that was the problem.
The best part, for this stove anyway, -- the ONLY tool needed was a #2 phillips screwdriver. Really. All told, maybe an hour of work, nothing intense. And free -- so if they both worked, it would have spared me ordering a part that didn't need to be replaced!