Brian
This is a new one to me, I have never read about it before, yours is a truly unique experience.
Your idea of getting in touch with Catalina is appropriate. The details of how to remove the sea hood to remove the hatch is the key. At the same time you could inquire about ordering a replacement, or consider having a local plastics company design and build a replacement.
It would be very interesting to the group if you could take some pictures while you are doing the work. especially the removal of the sea hood. I know we'd all be interested in how you resolve the issue.
Only other thing I can think of us to post the question with the C36 group on their website message board (requires joining, it's free) or perhaps Tom or Rod will notice this here and comment if they've had a similar problem with their almost identical construction details on the C36 Mark IIs.
Humorously: You could avoid the removal if you install a dodger - I can't think of any way to step on that puppy with a dodger installed, plus it'll keep the rainwater out of the crack!
