Old RF semiconductors?

[mr ed]

I am beginning to think that some rf semiconductor devices get weak as they age. I'm talking about 100k hours of service old. Supplies are right on and match a DC ref chip) The reason is, as I try to repair a rohde and schwarz SMIQ, I see some mmics with lower gain than expected. I have found dead rf devices (a fet and 2 mmics so far) but I seem to have low gains in some related circuits. I don't know what's going on here? Replacing one  mmic amp, I get a bit more db of rf (only running at 300Mhz). This repair has been a real grind.

Am I mistaken?