Check the brushes.  A bit of dust under one of them will keep it from running! I see you have had them out. That has s speed control rheostat on it. It could be that burned out. Look around for a local guy that works on electric motors and have him bird dog it. If the brushes are good, it must be the switch or the speed control  rheostat. It will take someone to use a continuity tester across the switch and the rheostat..........Cheers, Jim
ps Borrow a router to finish you project in the meantime!!!

Cheers, Jim ........................ Variety is the spice of life...............Learn something new every day