I replaced the tube TV on my Allegro too. First you have to get the wooden frame off. This was held in place with 4" long screws that are driven in to the frame from each side. Access to the screw heads was from the two side cabinets. In my case they were square headed screws. After they are removed you should be able to pull the frame off the front. From then on, there are little blocks that are screwed in at the top to hold the TV in place. Remove those and you can then lift the TV out of the box. Make sure to have help as they are quite heavy. Now all that said, that's how mine was done, I don't know what yours looks like.
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