The only way to be sure there are no pockets of grunge is to disassemble the whole filter housing and clean everything with fuel and a cloth. The only critical part of the process is when re-assembling, do not over tighten the body screws. It is only plastic and can be cracked by over tightening.
Mine get this treatment every time I see grunge in the bowl, so in the past 24 yrs, likely half a dozen times. I haven't ever had a problem. It only takes a few minutes.
I use a cloth below the filter housing as I disconnect the fuel lines (shut off first), an ice cream bucket below when I remove the old filter and get the housing off the wall, and to hold the whole mess while cleaning. If the fuel level in the tanks is above the top of the filter housing when on the wall, just open the valve on the line and when the fuel reaches the top of the filter and starts to come over the edges, tighten the top.
Your new filter will come with a new O ring for the top and for the closing T handle.
Watch when dis-assembling to see where the ball comes from, so you will have no doubts when you re-assemble.