I might be more help if you could post a pic, and yes , it should act as a weak motor if you wire it for that. It was just the old way of checking it. If it sat for a long time it could have corosion on the commutator [ where the brushes ride] , microfine sand paper will clean it up nicely. Some gens had an oil port behind the pulley for oiling the front bushing on the shaft. If it was over oiled it won't work. You might pull the cover on the voltage regulator to make sure it didn't blow as soon as you connected it to power.
02 edge 3.0 s/c manual 3.27 L/S, stock rims w 235 75 15's , e-fan mod , Underdog underdrive pulley , trac lock installed, hafta do somthing about those f-code t-bars