Fender Twin Pro Tube = 100 watt boat whistle

[booj]

Uncontrollable. Starts whistling as it warms up. Take out V2 or V3 and it stops. Re-soldered the board in the preamp section. Nothing looks bad or out of place. Swapping tubes doesn't help. V3 shows the strongest signal strength.
If you have experienced this problem and have a clue, your help appreciated. Awesome amp I'm sure when it works!
I can't paste a PDF file to look at, but the schematic is avialable at

http://www.fender.com/support/amp_sc...Amp_SchE45.pdf

[SatelliteAmps]

Usually whistling is a tube. But if you swapped them all out for good ones, then the next issue I would check would be either a coupling cap, or if possibly a wire that got moved too close to a different wire.

[booj]

I checked the voltages at pins 2 and 7 of V1, 2, and 3 to check for DC leakage. All readings were zero.
The wire thing seems the most likely, but as I mentioned all the wiring looks factory fresh and un-molested.

[SatelliteAmps]

If you take out V1 does it still happen?

[booj]

I think it still happens with V1 removed. It's back together. I'll get back with more clues hopefully.

[booj]

It was an open filter cap that filtered the section that was oscillating.