Modular replaceable units have caused a shift in the way people think these days. Things are automatically replaced, rather than repaired. Admittedly it is probably more efficient, time wise, to replace something rather than repair it. But sometimes, as with your grandfather's .22, a replacement part isn't available.
What's wrong with the trigger? Missing, broken, or badly worn? If it's merely broken or worn a competent gunsmith can probably repair it. If it's missing... well your pistol is probably a wall hanger, at least until you find a replacement.
