Remember Crossbow, the PLL shifts 455kHz in RX - so to do that it adjust VCO.
Were there any mods done to the Delta Tune section?
So scope R85, Tweak L22 - in RX...look for output.
You may have a bad "shift" cap.. R85 is not immune to drift either - they've changed this value from 180 ohms to 560 ohms thru the years and especially when they went to the YD (Youda) chip
IC2 is the main RX out - into L18 for TP3 and 1st IF.
IC3 is main TX out - you say you're ok to TX - that is L19...
Only other suspects in this for "shift" is IF section or L22 has a bad tuning cap - T/R Pin on the 29 is Pin 9 but the modifier in this is, that pin, for the shift to occur. Pin 10 is the "check" that looks at L22 - that cap is C94.
L23 uses 10.240 signal - and that goes to Pin 12/13 back at the PLL (Delta Tune) That is also the offset to the TX mixer from VCO TP4. You have TX - so the 10.240 seems ok - just the "Delta Tune" part gets' me.
There was once a TSB on the Cobra 19 Plus that although showed 1 cap - you have two now used in line - its is part of the loop detect "phase" section - I'm referring to C98 and C99 - should always change them for cheap insurance that you don't have one of those caps get flaky.
You would see it as a "impure" sine wave in the TP1 when you had just got RX in - and sine would improve as the caps "warmed up" and acted like they should. The change they exhibit is slight and slow (takes a while to see the difference - almost like a sawtooth) to see - but this section and the ways it acts - reminds me of my own efforts with Cobra repair, I always change these two caps.
