Having done a couple hundred 128K upgrades, the soldering is not extremely difficult. Cut the legs off the bad chip with a small nose wire cutter, then heat each pin from below and pull it out with needle nose pliers. The corner pins which connect to the power and ground planes inside the board will require a lot more heat than the rest since they are well heat-sinked. Then use a solder sucker or braid to clean the holes. Unless you replace ALL the RAM with sockets, don't socket the replacement chip, because the added capacitance of the socket will make that one chip slightly slower than the rest. One source of 4264 type chips is an Apple //e 80-column RAM card - usually cheap and plentiful. The earlier ones have socketed chips. The 256K chip will also work as a 64K. Good luck.