[ Adam Aceto wrote in 130304 MMDigest:

> The bass crescendo works perfectly and I know I had tested the treble
> crescendo within the year and it worked fine last time it was tested.

It sounds like you have ruled out tube problems, but check again.
Switch the treble crescendo with the bass crescendo unit and see if
it works properly.

Your problem does sound like a leak, and it's possible that one of
the valves in the crescendo unit might have a speck of dust or grit
blocking it, and the valve is not seating properly.

The other problem might be the gasket over the valves is leaking at
the edges.  See that all screws are moderately tight.

Bruce Clark