Can you make a change? So that Fire2 Jump works despite holding UP on the Joystick. And vice versa.
With such a fast game, accidental holding and blocking yourself from jumping happens quite often. And it can be frustrating ;)
I probably wrote it unclearly. Fire2 works for me (real C64 and emulator), but.. Accidentally holding down direction UP blocks the use of Fire2 for Jump. And vice versa. This affects when playing with a gamepad. And not important when playing one-button Joystick.
I use gamepad on real C64, USB device to DB9 adapter. Fire 1, 2, 3 works.