Hi everyone, I'm very new to all this - I just assembled my Jaycar kit theremin and am amazed I actually get a sound, considering the most I've ever done before electrically is wiring plugs. But I'm finding tuning very difficult, I can't get much range in either pitch or volume - does anyone have any tips? I don't understand anything about how to check voltages either, do I need to get some special equipment? Also the tuning changes a lot if I put the lid on, but there's no way to alter things without taking it off again - they said there was a hole to adjust VR2 but there isn't , should I drill one?