I htink you are smart to just replace old capacitors, even if they pass a test with a checker when put into use they may fail anyway. so long as the resistors are maked with colors go ahead and put your meter across them. normally as they fail they will drift up to a higher value or sometimes go open or intermittent. if they look blackened thats a sign too.
normally it is best practice to check resistors when they are not in circuit which means clipping or unsoldering a lead and that will make sure you aren;t getting an incorrect readiing because of some other route the current could take that may lead from one side to the other.
if there is a separate current path like this it can mess up your measurement resulting in a lower reading that if you unsoldered it .
I think it is important to realize that there can be no other circuit that can RAISE the value to a higher resistance this is electrically impossible.
so I’d say unplug it and so long as you can read the color bands just go ahead and do a quick check of each one in circut and try to locate any that are higher in resistance than the marked value.. then if you want ot be thorough sure unsolder one leg to avoid any possible confusion. Id suspect any great big ones first especially if they are blackened, or missing chunks etc. these big ones get hot and the heat causes failures..
I think you’ll find some radios where they are mostly all ok and others that have issues. maybe some were more reliable or maybe some were stored in places like hot attics or maybe some radios hjust have more mileage on them.
I remember some conversation around substituting solid state diodess for rectifiers. with a rectifier the current ramps up more slowly but solid state rectifiers are instant on. I remember where someone smarter than me electrically showed how to add some capacitors and maybe a resistor to slow the ramp up so there is a technique for this but I couldn’t remember or explain it to you but I think you’ll find others who may. I may also be confusing replacing older solid state diode stacks I’m thinking of the word .. its a poison, and those types diodes tend to go up in clouds of smoke.. they look like a stack of metal plates… I believe those older diodes also have a ramp up effect.
Phil .