Dont think you need to put yours in the oven as you have the spring clips on as in pic #2, your old ring may just pull off, if not you can try a heat gun or you may be able to cut the glue with a craft knife.
so take the clips off, be very careful (safty googles) prise them off with a flat screw driver, put driver in the hole and lever back and they should come off, do this to them all and the lense should pull of with a bit of wiggling and force. You then feed the ring wires through the rear of the cluster and glue the ring to the front of the inner lense, leave to set hard, I used Araldite clear glue, then put outer lense back on, start car remove rear bulb cover and turn on lights full for 1/2hr then put bulb cover back on , this gets all the moisture out of the light cluster.
VELVET BLUE UK INDIVIDUAL , IM THE LAST
UNITED WE STAND DIVIDED WE FALL
I stepped in a plate of Pasta the other day - now I have to worry about my Carbonara footprint!