Moisture and Ph have to be right also. You have to change the bedding (we use coconut coir with peat moss)- how often depends on how big the worm bin is. We feed them Purina worm chow with coffee dregs & crushed egg shells to help them digest the food. Only feed them what they will eat.
moisture - grab a handful of your bedding and squeeze, only a few drops of water should come out.
Ph - you need a meter or test strips. Shouldn't be a problem if you neutralize your peat moss with garden lime. One cup to a 5 gallon bucket. Coffee grounds aren't acidic. Don't feed your worms citrus fruit.