Now I am trying to do the Molecube (aka Nine Color Cube, Ball Sudoku Cube, etc.)

using the algorithms I learned from the regular 3x3x3 cube, I solved it a few times but sometimes (70% of the time) when I get to the last layer with every colors in the right place including the edges, I am left with two corner pieces that need to be swapped. This part is very similar to "6. Position Yellow Corners part" for regular cube, except that in regular cube's case, there seems to be only three possible cases (only one corner piece in the correct position, or none, or all in the correct position, I can always solve this with U R U' L' U R' U' L algorithm)

when in molecube's case, there are two corner pieces in the correct position and the rest of two corner pieces have to be swapped with each other. I cannot find an algorithm for this.

In short, when all other pieces are in the correct position, how do you swap two corner pieces in the last layer without moving the other pieces?

Any input would be greatly appreciated!!