Nice job!
You Solved MOST of the problem - you localized it to the AF amp.
The 44V has not been produced in a while - but if it has not been used in a while or you're just now getting to it, many of the Electrolytic caps are probably dried out and shorting - so what I would recommend that you locate
the POWER feed to it, There is an RX power rail input from the RX side - locate R56 - test both sides using a DVM - positive - with the other lead to foil ground not case ground FOIL (IF Can Shield Ground) type of ground and measure both sides of this resistor.
IF one side in RX meter shows close to 8V - the resistors other side nearly flat - Replace C35 - with another of rated value and working voltage. Should recover Receive but that also indicates the Electrolytic caps are, or starting to get, dried out and need to be replaced - so This area is one of the best places to start out in keeping the radios receiver working while you replace caps for as it - "recovers" you have noise in which to work by.
You will see that in your next test - where Collector and Emitter voltages of TR15 are going to be off.
C37 is another part that if it's dries out - will make the receive sound distorted - might want to replace that too.
So try acquiring Electrolytics as you can to replace the ones of similar values in this radio.
For if you don't, quirky problems like this will keep showing up until you replace all of them - or the parts they depend upon, might fail due to their dried out shorted condition.