Turns out mine is on the backside of the pump... looks like the only way to get to it is to unbolt the pump.

Perhaps I am missing something here, but I followed the raw water intake line from the thru hull, through the strainer, right to the pump... and out again. The only removable face at the pump is on the backside. Seems like a rather dumb design for a rather modern Yanmar. (repowered in 2008).