Some thoughts.
2) Difficult to see your diode and be certain of its bias. Are you certain the black cathode band is in the same direction it originally was? That would unlikely be the problem as you say it functions though with a lag, but make sure it is the same.
3) Do you still have the original components? Perhaps you could snap a photo of them so we can be sure the replacement components are in fact identical. I'm sure you have it right but we are all human.
4) The DIP IC is obviously functional, but we don't know the assignment of every pin and a partial failure could have occurred when the regulator failed...ICs have internal resistors, diodes, transistors that can conceivably function with one internal component faulty. Also, I can't see the ID for the chip. Perhaps you could offer the numbers printed on it and we can pull a datasheet. It might be a uC or OEM device but it might be a standard package too.
It is a pretty small circuit. Reverse engineering these is always helpful. That is if you can draw schematics. Backside photographs might help too.