[Radioroslyn]

Well that's a good start! Wouldn't replace the caps again that's probably not the problem. We know that the circuits using the 35W4, 12AV or AT6, and 50C5 are working just fine. So we'll need to look at the mixer (12BE6) and IF amp (12BA6). Safety first! When ever working on one of these sets ALWAYS USE A ISOLATION TRANSFORMER! this will isolate the ac line voltage from the chassis. If you like sticking your fingers into a wall outlet don't use one. It will also raise cane with your other test gear if they plug in to the wall.

Now truth be told I don't use one. What you can do is plug the set in turn it on and measure the ac voltage from the chassis to earth ground. Pull the plug turn it around plug it back in check the ac voltage. One way you will have 120vac and the other you will have some static voltage about 20v or so. That's is the way you always want to plug it in(with the static voltage on the chassis) when servicing.

Now for the troubleshooting. You can measure the resistors like Codefox said or you may want to look at some key voltages which may tell you whats going on. So let's go here:http://www.nostalgiaair.org/PagesByModel/173/M0003173.pdf Scroll down to the tube voltage listing. Mostly what you are looking for is the plate and screen voltages on the mixer and IF tubes. Have a look at the voltages and see what you can come up with. To answer your question if there is a part that is in parallel with the resistor yes you must disconnect one end if not you can measure it in the circuit.
Terry