I recently replaced all the larger sized capacitors on a Supermicro double slot-1 mainboard as they were bursting and swelling up. I can't get a decent-looking solder joint on one or more places, the print seems to be too far inside the platter. I did them all first with lead-free multicore, didn't work, so then sucked it all off and did them all again with 60% leaded multicore. Still no joy. Has anybody any advice or suggestions how to get decent looking joints? Thanks in advance and best wishes.