[stevehertz]

It really does depend on where you live, how good (sensitive/selective) an AM set is, and how good an aerial you have. In truth, even then there's not a great amount of stuff, but certainly enough to be of interest. I can get about five listenable channels on my AM sets. On FM, dozens of stations covering all manner of styles and subjects. But if you only listen to BBC R3 and R4 on FM, then that suggests to me that you have a narrow interest band - pun not intended and no offence meant, just an observation.

To me, a fully qualified though not so great electronics engineer, in a way (and you say UB), valve sets are easier to work on for many reasons; more room, valves easily changeable, large components, no PCBs to unsolder and ruin etc etc. Trannies can be a right pig to work on.

Also, one doesn't need to understand how 'every inch' of a circuit works in order to be able to work on it and fault find. I say just get stuck in and use all your knowledge to weed out the problem(s), many of which are the same type of thing over and over again on most sets, and they're not technical; poor switch and valve contacts, faulty wax & electrolytic caps, poor earths, dirty contacts on tuning caps and so on. Failing that, one can check the voltages on valves using a Trader sheet for reference.