LEDs cause signal to cut out at high gain levels? (RAT II)

[zarathustra]

I swapped out the stock Si diodes in my RAT II for a pair of red LEDs, and I found something odd. The LEDs sound great (very loud and crunchy), but when I turn the gain past 2 or 3 o'clock, the output signal starts to cut out, especially immediately after the pick attack. The higher the gain, the more it cuts out. Kind of sounds like something in the circuit is overloading? Anybody have this happen with their Rats and/or have any idea what could be causing it?

edit: I also just discovered that if I leave the stock Si diodes in and try to push the Rat with a gain pedal, I get the exact same result... signal cuts in and out.

[Guitarist1983]

I believe you could connect a 1M resistor between 9V+ and the gate pin of the FET buffer. I have not done this myself, but found this info in Jack Orman's Guitar FX Mods:Pro Co RAT, LEDs could drive the FET beyond its non-linear region.  You'll find this resistor in the Turbo RAT which is designed to use LEDs.
However, I wonder if the 1M resistor will adversely affect the performance of si or ge diodes.

"edit: the 1M resistor connects to the Gate pin.  see Output Buffer section in the above named book."

[bool]

An alternative would be to swap the fet for one with a higer Vgsoff, like a BF245C or a BF256C (watch pinouts).