Craig:

Lancair originally sold a hydraulic filter for the L-IV but later suggested removal because the filter didnt have a bypass capability, so I removed mine.

BTY, the L-IV hydraulic pump assembly does have an internal filter screen.  A friend sent me a couple of replacement screens when he sold his project. .  Not sure where they are, tho. (Memory 2nd thing to go......)  Regards, Bill Hogarty