wrote:

Three are used in the detector for the automatic level control (ALC)
circuit. Failure here probably wouldn=92t be catastrophic. Another
provides bypass in the output driver grid circuit, but is shunted by
some large resistors. I doubt failure would do much here either. The
last one provides bypass on the filament voltage to the linear master
oscillator (LMO). In this case, failure as a short could stress the
power transformer.

I'd test them... if they seem okay in-circuit, leave them there. If down
the road one of them fails, replace them all.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."