Mitchell 440A Bailarm Problem

[Complete Tangler]

I know, I know, 440's are old, but I tend to buy gear and stays with me until I either lose it or it breaks beyond repair.

My 440A is around 30 years old, its had a few things replaced (bailarm springs, anti-reverse spring etc), but the problem I have now is that the bailarm will not close, new spring fitted and proper tension on the screws, could it be the metal plate with the plastic half moon (under the spool) that could be the problem?

Thanks in advance for any advice.