After pulling the reel unit from the mower i found that its been modified in the past so its not an original part. The plastic part was screwed to a metal plate which ultimately weakened it by the looks of things.
Going by another thread Masport seem to still produce a part thats similar to what im after but im not 100% if its a good replacement. I might just buy it and see how it turns out. Itll be roughly $45 to my door.
As far as the belt goes im also not 100% sure if the belt that came off is the correct one. It did seem very slack but thats without the engine turning it over.
I have a 3D printer so if all else fails i might be able to reproduce the part. Have to get some CAD skills up though.