if your F18A has normal pins and not tall, which is the case for most for the TI-99 then using a machine socket will not work. This is because the diameter of the normal pins is much smaller than want a machine socket calls for and will not make a proper connection. Your dualwipe socket on the TI could need replaced with a new one if any of the contacts have lost their springy-ness (can't think of the right word).