Hi

Been working on a village for some time- was well lit and had no issues with monsters spawning. Now the light from most existing torches has suddenly dropped and I am getting monsters spawning in previously safe places (especially noticeable in my mine as it is now totally infested with monsters). 

Have been going around trying to replace all the torches but the new torches don't seem to be producing as much light or their light level drops the next night and I have to replace them again. 

Please help- currently unable to work in my village at night due to monsters spawning and cant get the mine cleared as the light level is not reliable. 

Thank you.