The other thing of interest is you said the batteries get hot when you turned it on. Switch number 1 before the 25 ohm rheostat is supposed to be a momentary on type. Most pictures I've seen show this switch to be a push button momentary on type. If the batteries get hot, then your rheostat and pot are turned all the way to zero. Try putting both 1/2 way instead. If it doesn't get hot then your wiring is probably okay.
All the schematics show a piezo transducer. So technically the way you have it setup is correct. Both your piezo devices are transducers according to the documentation. But a transducer will just make a click on initial power on. I do recall reading somewhere that the click sound is what tells you the tuning is correct. So you hold the switch on for 3 or 4 seconds, then release for 3 or 4 seconds. Then repeat the cycle. Each time you should hear a click if tuned properly.
When I built mine I used a piezo buzzer instead. A lot of builders use the buzzer instead. At least you know it is working with a buzzer. But then that isn't what the schematic shows. At the time I thought the schematic was a mistake. That's why I switched to a piezo buzzer. But what if the schematic is correct? And I flubbed up for switching to a buzzer? Like I said before, my Flux Capacitor didn't transport me through time. So you may just have to have a bit more patience with the tuning. Perhaps you are close to get it working correctly.
