Here is attempt number 2 at converting a TMCC steam engine to 4 chuffs using JB Weld. This was by far trickier than the 611 N&W because it seemed like the cherry switch was harder to get to...I don't think I had to remove the smoke unit on the 611; I had to on the 779. Again, it's not 100% perfect, but it's close enough for me. Next project is to update the mars light to the prototypical one that I purchased from a 2-railer.
Enjoy your weekend.