Hi Flighter,
Some have told me the Chinese repros are warped and don't seal properly. But maybe they are not fitting them correctly or the crappy cheap seals aren't working.
I have seen Italian reproduction lenses (not OEM Altissimo) a long time ago. These seem really high quality and may have been the Altissimo tooling reused with the OEM badging removed.
If you dig around it is still possible to find near perfect Altissimo and Butlers lenses.
Check out the for sale section of the forum. Errol Leslie advertised a week or so ago NOS lenses for a reasonable price.