Identify the two capacitors to be changed as circled. Make a mental note of their orientation in case you happen to have a different version of the board, or take a photo. It is likely that they are bulging at the top, and possibly leaking. (Not visible in the first photo as it was taken with the new capacitors in place)

Use the pocket knife to slice along the line shown in the second image to free the capacitor from the 'glue' that is sticking it to other components and do the same for the glue on the other capacitor. The image shows one of the bad capacitors removed and the remaining bad one (you can see the bulge here)

With the aid of a solder sucker or desoldering braid, desolder the capacitors - their location from the circuit side is highlighted in the third image (which shows both removed). You will need to pull on the capacitor from the component side of the board while heating each leg alternately, 'walking' it out of the board.

Ensure the holes are clear of solder so that the replacements will go in.