There will be a small hole in the barrel of the mic at the end of the barrel where it is attached to the frame. This is what you use the pin spanner for. If after cleaning, they are still out, you adjust the barrel by turning it with the pin spanner until the zero line on the barrel lines up with the zero line on the thimble. This can be quite fiddly to get right. Before you start adjusting it might be worth rechecking the mics at various times of the day to see if the reading stays the same. I'm thinking temperature variations here.
bollie7
bollie7