Your engine has two of them and they are about $35 each to replace the entire assembly. Very easy to do yourself. I would do them regardless with your engine hours. I do them as preventative maintenance every three seasons up my way due to the ethanol.
Missed your question on location........
Your VST is blocking them a bit. I remember unbolting that and moving it aside when doing LP pumps on a 150 HPDI I owned on another boat.