This valve cover is from the drivers side of my AJ27, I was informed this is very common the plastic cover I guess for the part load breather often breaks. Looking for the best solution. Personally I really do believe a good JB weld job will do the trick but I am very open minded and am willing to listen to you experts. As a 25 year old with the love of such a beautiful vehicle I am very glad I can reach out for wonderful advice. Happy New Year to everyone across the world!

 

If that video sums up the entirely of your problems, you are very lucky.
I had that, too, and I simply used high-temperature-RTV-silicone (that red stuff, which you use on the uneven spots on top of the valve cover gasket).
I applied that RTV and then put the lid (which is loose under your valve cover) back into position and let ti dry before putting the valve cover back on.

you can see what I did in this thread of mine:
https://www.jaguarforums.com/forum/x...covers-266148/

As you can see, I also had a "serious issue" with those valve covers, which I also fixed, however, meanwhile I also ordered new covers (but had no need yet to install them).

 

Yeah, just clean it up and JB weld it. Good as new!

 

Indeed. Given the value of the car, the cost of a new replacement (if its even available) and the relative ease of removal and reinstallation, I would be inclined to try to glue it first too.