Believe it or not, your parts list checks out ok.
The Losses are due to factors further upstream from the Final and Driver - or Down Stream if you are having heating up issues - but SSB signal - when you have TOO high of a signal gain from a previous stage - kills the signal - it degrades it - from OVERAMPLIFICATION further down the strip from where ever this caused the original condition.
So that means - since IF is mixed in from TWO locations - the inputs from BOTH locations needs to be EQUAL.
That may mean a resistor Check /Verify - swap - fix - at two locations to help balance the PLL IF and Clarifier's IF to be equal and balanced so the mixing can occur with less distortion. Tweaking coils is great to help but only go so far - that is what they're there for to take the unbalanced and finely tune it to meet level - 2 - level so the BYPRODUCTS are less and you don't get too much distortion.
I can tell you from experience - R231 and R232 - they are a *<EXP>* to find but are two resistors that enter IF signal into L43 and L44 - one "starts" at 100 Ω (R231) while the "other" is 560 Ω (R232) - and that is on their parts list, but in real life? No not always those values - L44 or L43 can peak in varying amounts of RF at any given moment in production forcing them to change on the Fly - so they may have subbed values - or if the radio passed QC and was sent out (if it was even checked) - does not mean it was verified - and they just may have kept those two resistors as listed on the schematic.
This becomes the problem for you when AM or FM modes are great, signal looks good and have power.
Why does SSB? SuX? It's in the finer details of SSB mixing, it's trickier, you have IF from one section flooding the Mixer with it's RF, the other side has IF that arrives when you talk - so the mixing effects has to take the weaker signal and not over amplify the other IF in the process - the dynamics of mixing - so the FILTER then has to do all the work in removing the lower IF ringing but allow the 27MHz mixed stuff thru - so if you understand this entire paragraph - you're doing better than most.
So L43/L44 mixer - and possibly R231 and R232 will have to be altered (by age too) to balance the IF signal better.
The Losses are due to factors further upstream from the Final and Driver - or Down Stream if you are having heating up issues - but SSB signal - when you have TOO high of a signal gain from a previous stage - kills the signal - it degrades it - from OVERAMPLIFICATION further down the strip from where ever this caused the original condition.
So that means - since IF is mixed in from TWO locations - the inputs from BOTH locations needs to be EQUAL.
That may mean a resistor Check /Verify - swap - fix - at two locations to help balance the PLL IF and Clarifier's IF to be equal and balanced so the mixing can occur with less distortion. Tweaking coils is great to help but only go so far - that is what they're there for to take the unbalanced and finely tune it to meet level - 2 - level so the BYPRODUCTS are less and you don't get too much distortion.
I can tell you from experience - R231 and R232 - they are a *<EXP>* to find but are two resistors that enter IF signal into L43 and L44 - one "starts" at 100 Ω (R231) while the "other" is 560 Ω (R232) - and that is on their parts list, but in real life? No not always those values - L44 or L43 can peak in varying amounts of RF at any given moment in production forcing them to change on the Fly - so they may have subbed values - or if the radio passed QC and was sent out (if it was even checked) - does not mean it was verified - and they just may have kept those two resistors as listed on the schematic.
This becomes the problem for you when AM or FM modes are great, signal looks good and have power.
Why does SSB? SuX? It's in the finer details of SSB mixing, it's trickier, you have IF from one section flooding the Mixer with it's RF, the other side has IF that arrives when you talk - so the mixing effects has to take the weaker signal and not over amplify the other IF in the process - the dynamics of mixing - so the FILTER then has to do all the work in removing the lower IF ringing but allow the 27MHz mixed stuff thru - so if you understand this entire paragraph - you're doing better than most.
So L43/L44 mixer - and possibly R231 and R232 will have to be altered (by age too) to balance the IF signal better.