How do you change warter intake screen in 1977 85 hp johnson lower unit?

my engine has sat for 10 yrs and I am changing impeller and also my water intake screen has some of mesh broken. Is it necessary to replace and how? Also I have a new impeller and do I need any other parts before I tear it apart? Thanks DaveHow do you change warter intake screen in 1977 85 hp johnson lower unit?might as well change the gear lube while you're at it. the impeller is all you need unless the wear plate is very worn. the intake screen just pops in and out, shouldn't be a problem. remember to turn the driveshaft clockwise only when replacing the impeller.