Window parts are things like locks, handles, rollers, keepers, springs Fasteners, plungers etc. etc. that are on our windows to do some kind of function
Most window parts you can't get anymore cause the manufactures have either belly-ed up. Or have moved on into making the newer type of vinyl windows and there isn't any market for this old stuff anymore. there are some new windows parts in packages
try to match yours up with these or bring in your samples.