you need to decide for yourself what works best for you.
the last thing you want to do is to heat the joint then pull the caps. if you heat it too
much, then you might use pliers to pull. you could crush the cap (polystyrenes).
you will leave a glob blocking the replacement cap. third you will be using
very old (probably older than you) leftover used solder. and probably with NO
flux, damage the new replacement. then overheat the pcb and maybe lift those
traces that are tricky to fix.
the goal is to use enough heat for the SHORTEST POSSIBLE TIME, and
very quickly remove the solder. then the component drops off the board,
the through hole is clean, the board is NOT damaged. then replacing
the new component is a matter of mounting the cap, and using solder
(that has flux) to solder the component onto the board.
your tools and the device will dictate how effective it will be. cheap pencil
irons, static-free pencils, or temperature controlled - from bad to good.
solder suckers put lots of heat on the joint because the solder wick needs
to be heated up along with the joint. solder suckers require good hand-eye
corrdination, heat with iron with one hand, immediately switch to other hand with
sucker and release pump. or solder pump station
some notes, you may wish to clean up the board after pulling component.
do not attempt SMD boards as a beginning (there's a larger base of data
required for this OVER simple through-hole soldering).
UNDER NO CIRCUMSTANCES ARE YOU TO "FIX" CAP ORIENTATION
IF YOU SEE STENCILING ON THE BOARD THAT DOES NOT MATCH THE
COMPONENT AS IT WAS WIRED.
so to test and develop your skills. buy a working (or non working) unit.
remove caps and resistors and then solder them back in. find out
all the ways to do this and look for repeatability, reliability, speed
and correctness. reliability means that working unit continues to
operate after your work.
you'll also need a schematic, board layout, parts list and compare
this to the actual board - ALL four must agree in type, number,
value (and voltage if its a cap), etc. do not substitute unless
you have trusted information that you understand and can do.
good luck - post your summary and results with pictures if you wish
to return help to others that follow you. recorded mistakes OK to
help other learn.