Parker 45 converter

I'm finding that my Parker 45, equipped with a Parker converter, will
not draw ink from the bottle when it's installed in the pen... but it
will when I remove it from the pen and insert it directly into the
bottle. This is not a pen I use very often.

The problem sounds to me like an air leak at the point at which the
converter mounts onto the body of the pen (collector?). Any suggestions
for gasket repair, or parts source for a NOS (or does a new one fit?)
converter?