Realign carefully the "circled blue" core coil and the "circled red" core
coil in metallic case near the PLL IC. Your PLL is not "locking" the VCO and
maybe the low power is due to extremely dirty output not in 27 mhz range, so
your final stage is driven by noise.
HTH, 73.

I think HTH's idea is sound... along those lines... the local
oscillator might also be stopping. This should be easy to confirm by
looking around the loop with a scope. I also had another thought that
your TX source might be intermittant. As you may or may not know...
most transceivers have multiple B+ sources. These sources are usually
engaged to various circuits... some in TX and others in RX. You should
definately check these sources for stable operation.
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