I don't know much about electronics, so I don't know how to swap out the smoke resistor, GUNRUNNERJOHN.
Which one of those smoke fluids you listed produce the most smoke output, BRIANEL_K-LINEGUY?
Is there a difference between the three Lionel fluids I have (#6-02920, #909 & #6-2909)? If yes, can either of the older smoke fluids or the 3rd party fluids damage the #8624's smoke unit?