Thetford Grill Problem

I have a problem with the grill in our Thetford cooker but I'm guessing it is not a common fault. The grill burner tube is supported by two metal rods about 6mm dia going vertically up from the burner tube to the body of the cooker, one near the front of the burner tube and one near the back. The front rod has broken away at the top of the rod allowing the tube to drop down at the outer end. It doesn't appear that the rod is threaded  and so I cannot figure out how this was held in place. It's possible to push the rod back up into the hole where it should be but there is nothing obvious to retain it so it just drops down again.

Has anyone else had a similar problem and, if so, how was it rectified?

The cooker is a Thetford S-CK13000 (three burner + electric hotplate). The caravan is 5 years old.