The issue is probably that the walls around the spawner are obstructing the light from the torches. Just spread out the light better. If it doesnt make sense, look into the mob spawning figures for regular vanilla mc. If things still dont make sense post pictures as this may make the lighting issues obvious.
Heh yeah. If you want to keep the spawner but need to change the room its in etc. the best strategy is probably to run in there with a Diamond dolly and just grab it before it can spawn off too many. Then you can keep it in a chest or something till you are ready to put it back up again.