[julie_m]

If you don't know which valve belongs in which position in the set, you can work it out just by seeing what is connected to it. In a radio receiver, each valve is associated with, and connected to, at least one other major part; so you just need to follow the wiring. The rectifier (EZ40 or EZ41) goes to the power transformer and main smoothing capacitor can. The audio output valve (EL41) goes to the speaker transformer. The Frequency Changer (ECH42) goes to the tuning capacitor. The I.F. amplifier (EAF41) goes to both I.F. transformers; that just leaves the detector / audio preamp (EBC41) to go in the last empty position.

Both EZ40 and EZ41 are full-wave rectifiers, and have the same electrical pinout. The EZ40 is rated for a higher anode current (90 mA as opposed to 60mA for the EZ41), but consumes more current in its heater (580mA aot 400mA). The EZ41 will be fine in this set, as it is only powering 4 other valves. A fancier set with a push-pull audio output stage, a "magic eye" tuning indicator and possibly an additional RF amplifier stage would need more HT current for the additional valves, and so would require an EZ40 (and a larger power transformer). (Note that the 9-pin rectifiers valves are numbered the other way round! EZ81 is the heavier-duty sister of the EZ80.)

While you are tracing the set's wiring, work backwards from pin 6 (the grid) of the EL41 until you come to a capacitor, probably between 10nF and 100nF. If you don't do anything else to the set, please replace this one capacitor with a modern polyester or polypropylene capacitor of the same value or as near as possible (22 for 20, 47 for 50). If it's faulty, it can ruin the speaker transformer and the EL41.

If in doubt, post pictures!