Nach H.F.Meyer Low Pitch C - low note problems

[n9yty]

I have been away for a very long time, life has twisted and turned and I haven't been able to do much with my flutes/whistles. However, someone has just given me a Nach H.F.Meyer Low Pitch C flute. It has had a crack in the head section below the tuning slide, which has been repaired. I'll attach a picture, but I'm not sure why that would be causing the issues.

I took the head section of my M&E flute, which is not quite the same size but very close, and had some interesting results. Basically, every combination that doesn't involve that piece works fairly well, even though the tuning slides don't fit into each other I can get just enough to hold it to test. Intonation is horrible, of course, but the notes sound.

Some combinations:
The entire head section of the M&E on the Meyer works fine
The entire head section of the Meyer on the M&E body has the same no-low note problem
The "above the slide" portion of the M&E on the cracked section of the Meyer has the problems
The "above the slide" portion of the Meyer with the "below the slide" portion of the M&E works OK

So it seems that however the crack was repaired was not sufficient, as when that piece is being used I can't get the low notes to sound.

Is there anything that can be done to fix it?

[For some reason, the images are not showing up, but if I right-click and say open in new tab/window, they are fine]

[n9yty]

After reading more threads here, I wrapped some tape around that lower section of the head piece below the tuning slide, not around the joint as much as just around the section itself and now it plays much better. I'm confused, though, because it seems like that whole section has the metal inner lining, so how is it leaking air? But yet obviously something is doing something. LoL

[intheair]

Looking at your picture, I see what looks like glue smeared on the inside surface of the barrel joint either side of the crack, plus the crack itself is maybe not filled level with this inside surface. I'm no expert, but my guess is this unevenness of the surface provides one or many small 'channels' for air to bypass the thread or cork and escape to the outside world.